DRINKING WATER STANDARD SETTING

   QUESTION-AND-ANSWER PRIMER
     U.S. ENVIRONMENTAL PROTECTION AGENCY
             OFFICE OF WATER'S
   OFFICE OF GROUND WATER AND DRINKING WATER
             401 M STREET, S.W.
           WASHINGTON, D.C. 20460
               November 1994

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                        INTRODUCTION

      This primer was developed to answer questions posed by various segments
of the public, from  students to public utilities to Congress, about EPA's drinking
water regulations under the Safe Drinking Water Act.  The primary audience,
however, for this publication is State and local government officials.  Because of
the wide range  of audiences,  each question has a short answer in the first
paragraph, followed by a lengthier, more detailed, answer.

      This publication follows a question and answer format.   It is organized
thematically in four segments:

      •     Section I:   Authorization/Applicability/Coverage of Drinking Water
                        Standards,

      •     Section II:   Drinking Water Standard Components/Definitions,

      •     Section III:  Maximum Contaminant  Level  Goals  (MCLGs)  and
                        Maximum Contaminant Levels (MCLs)  and

      •     Section IV:  Requirements  Established  by  NPDWRs other than
                        MCLGs and MCLs/TTs.

      Section 1  answers questions concerning who has authority to set  and
enforce drinking  water regulations, who  has to follow these  regulations and the
extent of their coverage. Section II  discusses the definition and background on
components of drinking water regulations,  such as Maximum Contaminant Level
and Treatment Technique. Section III is further divided into two sections: Section
A discusses MCLGs and how EPA derives  them, and Section B discusses MCLs
and  how EPA establishes them.   Section IV discusses other enforceable
requirements, such as monitoring, recordkeeping, reporting and public notification.

      There  are four  appendices to  this primer:   (1)   Appendix  A  -
Applicability/Coverage for each regulated contaminant; (2) Appendix B - MCLGs,
MCLs, Health Effects and final and effective dates for each regulated contaminant;
(3) Appendix C - the most current Drinking Water Priority List and (4) Appendix D -
 Secondary Drinking Water Regulations.  A list of acronyms used in this primer
appears just after the table of contents.

      Each question/answer has been designed so that it may be taken out of
this publication and still be comprehensible.  However, they are also intended to
fit  together with the  questions/answers  in the same  section,  so that each
question/answer builds  on  information  from the  last question/answer.   The
margins have been set so that this publication can be placed in a looseleaf binder.
As information changes, the primer will be updated, and the updated pages will be
available to replace those superseded.   When the SDWA is reauthorized by
Congress, this primer will be updated.

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                               Table of Contents


 I.     Authorization/Applicability/Coverage of Drinking Water Standards


 1.1.    By what authority does EPA promulgate (i.e., publish as a final rule in the Federal
       Register) drinking water standards?	1

 I.2.    Who is subject to EPA's regulations?	2

 I.3.    What is a Public Water System (PWS), and how many types of systems are there?  ... 2

 I.4.    What is a Community Water System (CWS)?	3

 I.5.    What is a Non-Community System (NCS)? 	,	3

 I.6.    What is a Transient, Non-Community Water System (TNC)?	4

 I.7.    What is a Non-Transient, Non-Community Water System (NTNC)?  	5

 I.8.    What is a Consecutive Water System?	,	5

 I.9.    Does every EPA drinking water regulation apply to all types  of Public Water Systems?  6

 1.10.   What about household or "private" wells?	:	e

 1.11.   How does EPA enforce its drinking water regulations?	7

 1.12.   Who ensures the safety of materials and contact surfaces used by drinking water
       systems?	8

 Sources cited in Section I	10

 II.     Drinking Water Standard Components/Definitions

 11.1.    What is a National Primary Drinking Water Regulation (NPDWR)?	11

 II.2.    What is a Maximum Contaminant Level Goal (MCLG)?	11

 II.3.    What is a Maximum Contaminant Level (MCL)?	12

II.4.    How is a Maximum Contaminant Level Goal (MCLG) different from a Maximum
       Contaminant Level (MCL)?	12

li.5.    What is a Treatment Technique (TT)?	13

II.6.    How do an MCL and a Treatment Technique differ?	14

II.7.    How many National Primary Drinking Water Regulations (NPDWRs) have been
       promulgated?	14

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                        Table of Contents (Continued)

11.8.           How many of these standards are now effective?	16

H.9.           When would there be fewer standards effective than final?	 16

11.10.          How many NPDWRs are currently proposed but are not yet final?  	17

11.11.          Will any primary drinking water regulations be proposed or finalized in
              the future?	17

11.12.          Does EPA have a list of what contaminants will be proposed or finalized in
              the future? .:	18

11.13.          Do the contaminants on the Drinking Water Priority List (DWPL) have MCLGs
              and MCLs?		:	19

11.14.          How does EPA choose which contaminants to place on the Drinking Water
              Priority List (DWPL)?	 19

11.15.          Is the DWPL ever revised?  	20

11.16.          Are promulgated standards ever revised?	20

11.17.          What is a Secondary Drinking Water Regulation (SDWR)?  	20

11.18.          How is a National Primary Drinking Water Regulation (NPDWR) different
              from a Secondary Drinking Water Regulation (SDWR)?	21

Sources Cited in Section II	22

III.           Maximum Contaminant Level Goals  (MCLGs) and Maximum
              Contaminant Levels  (MCLs)
A.  MCLGs

III.A.1.         How does EPA set a Maximum Contaminant Level Goal (MCLG)?  ........ 23

III.A.2.         What is EPA's reasoning for setting MCLGs of zero?  	23

HI A3.         When setting the MCLG, what are Categories I, II and III, and how do these
              categories affect the MCLG setting process?	24

III.A.4.         What is a cancer classification?	25

III.A.5.         How many cancer classifications exist, and what does each classification
              mean?	26

III.A.6.         How does EPA determine which cancer classification to assign to a
              contaminant?	27

lll.A.7.         What is a cancer risk range, and how is it derived? 	27

ii

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                           Table of Contents (Continued)
  III.A.8.         What are the NOAEL/LOAEL levels, and how are the levels derived? 	28
  III.A.9.         What is an uncertainty factor, and how is it derived?  	28
  III.A.10.        What is a Reference Dose (RfD), and how does EPA determine it?'	29
  HI.A.11.        What is a Drinking Water Equivalent Level (DWEL), and how is it derived?  .. 30
  III.A.12.        What is the Relative Source Contribution? 	31
  Sources cited in Section III.A	      32
  B.  MCLs
  III.B.1.         How does EPA set National Primary Drinking Water Regulations (NPDWRs)?   33
  III.B.2.         What technological concerns are factored  into this determination?  	34
 III.B.3.         What are BATs, and how are they involved in setting MCLs?   	34
 III.B.4.         How are BATs chosen?	    35
 lll.B.5.         Do water systems have to install BATs?	36
 III.B.6.         What cost concerns are factored into the MCL determination?  	37
 III.B.7.         Does EPA factor in nationwide costs when setting NPDWRs?	37
 III.B.8.         Are health risks also factored into the determination of MCLs?	38
 III.B.9.         What are analytical methods, and how are they involved with MCLs?  	38
 III.B.10.         What is an MDL?		;                     39
-III.B.11.         How is an MDL derived?	39
 III.B.12.         What is a PQL?	40
 III.B.13.         How is a PQL derived?	 . .                     40
 I1I.B.14.         How do the MDL and PQL differ?	      41
 Sources Cited in Section III.B	            42
                                                                                     iii

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                         Table of Contents (Continued)

IV.    Requirements Established by NPDWRs Other Than MCLGs and
       MCLs/TTs

1V.1.    What other requirements are established by NPDWRs?  . . . .	43

IV.2.    How frequently do Public Water Systems (PWSs) have to monitor for regulated
       contaminants?  	44

IV.3.    Where must Public Water Systems (PWSs) monitor for contaminants? 	44

IV.4.    Does the source of water (i.e., surface water or ground water or a mixture of the two)
       affect the way systems monitor?	45

IV.5.    What other factors can affect monitoring?  	45

IV.6.    What is "unregulated" contaminant monitoring?	46

IV.7.    What are the reporting requirements to the State and/or EPA?	46

IV.8.    What records do the Public Water Systems (PWSs) have to maintain? ........... 47

IV.9.    Are these records available to the public?	:	48

IV.10.  How long must PWSs keep their records?	48

IV.11.  What is public notification,  and when do PWSs have to do it?	48

IV.12.  What is mandatory health effects language, and when would systems use it "for public
       notification?		-	49

IV.13.  Do all regulated contaminants have mandatory health effects language?  . .	50

Sources Cited in Section IV	• • 51


APPENDIX A:

       Table 1: Applicability/Coverage  by Contaminant
       Table 2: Applicability/Coverage  by Rule

APPENDIX B:

       Table 1: Contaminants Regulated under the Safe Drinking Water Act
       Table 2: Final and Effective Dates by Rule

APPENDIX C:   Drinking Water Priority List

APPENDIX D:   Secondary  Drinking Water Regulations
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Acronym:

BAT
BTGA
CERCLA
CRAVE
CFR
CWS
D/DBPs
DWEL
DWPL
EPA
FR
FY
GAC
IOC
LOAEL
MCL
MCLG
MDL
mg/l
MFL
NCS
NPDWR
NOAEL
NTNC
OST
PE
PQL
PWS
PWSS
RfD
RIA
RSC
SDWA
SDWR
SMF
SOC
TNC
TT
URTH
VOC
                            List of Acronyms
 Term Spelled Out:

 Best Available Technology
 Best Technology Generally Available
 Comprehensive, Environmental Response, Compensation and Liability Act
 Cancer Risk Assessment Verification Endeavor
 Code of Federal Regulations
 Community Water System
 Disinfectants/Disinfection Byproducts
 Drinking Water Equivalent Level
 Drinking Water Priority List
 Environmental Protection Agency
 Federal Register
 Fiscal Year
 Granular Activated Carbon
 Inorganic Compound
 Lowest-Observed-Adverse-Effect-Level
 Maximum Contaminant Level
 Maximum Contaminant Level Goal
 Method Detection Limit
 Milligrams per Liter
 Million Fibers per Liter
 Non-Community System
 National Primary Drinking Water Regulation
 No-Observed-Adverse-Effect-Level
 Non-Transient, Non-Community
 Office of Science & Technology
 Performance Evaluation
 Practical Quantitation Level
 Public Water System
 Public Water Supply Supervision
 Reference Dose
 Regulatory Impact Analysis
 Relative Source Contribution
 Safe Drinking Water Act
 Secondary Drinking Water Regulation
 Standardized Monitoring Framework
 Synthetic Organic Compound             , '••
Transient, Non-Community
Treatment Technique                     ;
 Unreasonable Risk to Health
Volatile Organic Compound

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     I. Authorization/Applicability/Coverage of Drinking Water
                               Standards
 1.1.
By what authority does EPA promulgate (i.e., publish as a final rule in
the Federal Register) drinking water standards?
       The Safe Drinking Water Act (SDWA) requires EPA to establish Maximum
 Contaminant  Level  Goals  (MCLGs)  and  National Primary  Drinking  Water
 Regulations (NPDWRs) for 83  contaminants listed by Congress  and for other
 contaminants that, in the judgment of the Administrator, may have adverse effects
 on the health  of persons and that are known or anticipated to occur in  Public
 Water Systems (SDWA, Section 1412(b)(3)(A)).  Therefore, EPA's Office of Water
 develops drinking water regulations by the authority granted to EPA under the
 SDWA. Using this authority, EPA develops MCLGs and NPDWRs to ensure that
 the nation's public drinking water systems provide drinking water that protects
 public health (40 CFR 141.2).

       Congress enacted the SDWA on December 16,1974, and amended it on
 June 19,1986. The 1986 Amendments strengthened the original Act by setting up
 a timetable for EPA to promulgate NPDWRs. The 1986 Amendments also required
 EPA to establish  programs for sole source aquifers, wellhead protection and
 underground injection control.

      The Act authorizes EPA to regulate contaminants in two  ways. EPA may
 establish Maximum Contaminant Levels (MCLs) or EPA  may  require use of a
 Treatment Technique (TT) if the Agency  finds  that it is not  economically or
 technologically feasible to ascertain the level of a contaminant (SDWA,  Section
 1412(b)(7)(A)).  The Act,  in addition, required EPA to promulgate a regulation
 specifying criteria under which filtration is required for surface water sources
 (SDWA, Section 1412(b)(7)(C)) and a regulation requiring disinfection for all Public
 Water Systems.
For more information about these topics:

NPDWRs


DWPL
                                   Refer to these questions:

                                   11.1, II.3, II.5-11.12, 11.18, III.B.1, IV.1,
                                   IV.7-IV.8andlV.11.

                                   11.12-11.15.

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1.2.   Who is subject to EPA's regulations?

      Public  Water  Systems  (PWSs)  are  subject  to  EPA's  drinking  water          flip
regulations. These regulations apply to individuals, industries, businesses, private          ^^
water systems or schools only if such entities fall under the SDWA definition of a
PWS.

      These requirements do not apply, however, to a system that meets all of the
criteria specified in Section 1411 of the  SDWA. This section states that federal
drinking water regulations will not "apply to a public water system --

      (1)    which consists  only of distribution and storage facilities (and does
            not have any collection and treatment facilities);

      (2)    which obtains all of its water from, but is not owned or operated by,
            a public water system to which such regulations apply;

      (3)    which does not sell water to any person; and

      (4)    which  is not a carrier which conveys passengers in  interstate
            commerce"  (SDWA,  Section 1411).

For more information about these topics:            Refer to these questions:

Applicability                                 1.1 and 1.9 -1.10.

PWSs                                     I.3 -1.8.


1.3.   What is a Public Water System (PWS), and how many types of systems
      are there?

      A PWS is a system that provides piped water for human consumption and
regularly serves at least 25 persons or has at least 15 service connections.  A PWS
may receive its water from ground water sources, surface water sources or a
combination of the two sources; in some  cases, one PWS may purchase all or part
of its water from another PWS.

      The SDWA defines a PWS as a "system for the provision to the public of
piped water for human consumption, if  such system has at least fifteen  service
connections or regularly serves at least twenty-five individuals. Such term includes
(A) any collection, treatment,  storage and distribution facilities under control of the
operator of such system and used primarily in connection with such system, and
(B) any collection or pre-treatment storage facilities not under such control which
are used primarily in connection with such system" (SDWA,  Section 1401(4)).
EPA interprets 'regularly serves' to  mean the system serves at least 25 persons on
a daily basis  for at least  60  days.  Service connections are pipes between the
distribution system mains and any building or structure.

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      Although PWSs can be operated by municipalities or other government
organizations,  PWSs can also be owned and operated by an individual or by a
company.  PWSs come in a variety of sizes, as well, ranging from 25 individuals
served (or fewer as long as a PWS has at least 15 service connections) to several
million served.   As long  as a system meets  the  criteria listed in the above
paragraph, it is considered a PWS, regardless of its size or whether it is operated
by a public or private entity.

      There are two types of PWSs:  Community Water Systems  (CWSs) and
Non-Community Water Systems  (NCSs).   NCSs can be further  divided into
Transient  Non-Community Water Systems  (TNCs) and Non-Transient Non-
Community Water Systems (NTNCs).  These classifications are also not based on
size; they are based on the type  of user population a system serves (for more
information on types and sizes of PWSs, as well as the requirements each has to
follow, see Appendix A).  A special type of water system is called a consecutive
water system.  Each type of water system is discussed at length below.

For more information about these topics:           Refer to these questions:

PWSs                       .              I.2 and I.4 -1.8.


1.4.   What is a Community Water System (CWS)?

      A CWS is a PWS that serves at least 15 service connections used by year-
round residents or regularly serves at least 25 year-round residents, e.g., homes,
apartments  and condominiums  that are occupied year-round  as  primary
residences (40 CFR 141.2).

      According to EPA's  FY 1993 National  Compliance Report, there are
approximately 57,561 CWSs in the  United States, providing water to approximately
242,679,000 persons (Compliance Report, p. 11).  CWSs serve more users than
any other type of PWS even though there are more Non-Community Systems
(NCSs)  operating in the United States.

For more information about these topics:           Refer to these questions:

PWSs                                     I.2 -1.3 and I.5 -1.9.


1.5.    What is a Non-Community System (NCS)?

      A Non-Community System (NCS) is a PWS  that is not a CWS, i.e., a
system that does not serve at least 15 service connections used by year-round
residents or regularly serve at least 25 year-round  residents (40 CFR 141.2).
NCSs can be classified as either Non-Transient or Transient systems and
exclusively serve users in one or more of a variety of non-residential settings
including schools, office buildings, campgrounds, restaurants and highway rest
areas.

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      Approximately 21,273,000 persons get their water from 133,706 NCSs
(Compliance Report, p. 11). Although there are more Non-Community Water
Systems than Community Water Systems (133,706 Non-Community compared
to 57,561 Community Water Systems), Non-Community Water Systems supply
drinking water to fewer customers than Community Water Systems. NCSs tend
to be small to medium in size (serving up to 10,000 individuals) rather than
large (serving more than 10,000 individuals).

      There are two types of NCSs:  Transient Non-Community Systems and
Non-Transient Non-Community Systems. A system is classified as either
Transient or Non-Transient by the length of time its users drink water from that
system. In other words, systems that serve the same individuals daily for at
least 6 months per year are classified as Non-Transient and systems that serve
the same individuals less than 6 months per year are classified as Transient
Water Systems! These types of water systems are discussed in further detail
below.

For more Information about these topics:            Refer to these questions:

NCSs                                      1,6 -1.7.

PWSs (other than NCSs)                       1.2.-1.4 and 1.8 -1.9.


1.6.   What is a Transient, Non-Community Water System (TNC)?

      A Transient,  Non-Community Water System (TNC) is a PWS that serves at
least 25 people daily; however, it serves the same individuals for less than 6
months, e.g.,  campgrounds, parks and gas stations (40 CFR 141.2).

      EPA considers 98 percent of the 109,714 TNC water systems to  be very
small, i.e., they serve between 25 and 500 persons on any given day (Compliance
Report, p. 17).  The population estimated to use these,systems at one  time or
another during the  year is 15,428,000.

      TNC water systems do not usually serve the same individuals on a daily
basis.  They cannot serve 25 or more of  the same individuals longer than  six
months a year and keep their status  as  a Transient, Non-Community Water
System.  Examples of such a system include campgrounds, restaurants or rest
stops that have their own water supply source.

For more information about these topics:            Refer to these questions:

NCSs                                      I.5 and I.7

PWSs (other than NCSs)                       I.2 -1.4 and I.8 -1.9.

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 1.7.   What is a Non-Transient, Non-Community Water System (NTNC)?

      An NTNC is a PWS that serves at least 25 of the same persons for over 6
 months per year (40 CFR 141.2).  A typical example of an NTNC is a school or an
 office building that has its own water source, such as a drinking water well.

      Although there are more TNCs, NTNCs serve more people than Transient
 ones.  According to EPA's FY 1993 National Compliance Report, approximately
 23,992 NTNC water systems serve 6,315,000 persons. As with Transient systems,
 EPA deems most of the NTNC systems to be very small systems, serving between
 25 and 500 persons (Compliance Report, p. 15).

      To be an  NTNC, a system must have its own water; source and serve at
 least 25 of the same persons over 6  months per year.  Businesses that get their
 water from a  Community Water System and  do nothing to modify it are not
 considered to be NTNC systems and thus, are not subject to EPA's drinking water
 regulations.

 For more information about these topics:           Refer to these questions:

 NCSs                                     I.5 . i.e.

 PWSs (Other than NCSs)                       I.2 -1.4 and I.8 -1.9.
1.8.   What is a Consecutive Water System?

      A Consecutive Water System exists when one PWS supplies water to one
or more other PWSs (40 CFR 141.29).  This type of water system may be either
a  CWS, an NTNC  or a TNC water system.   A common situation involving
Consecutive Water Systems is when one system, called a. bulk water supplier,
supplies water to other PWSs.  For consecutive systems, EPA allows the States
to decide how each system will conduct monitoring. In some cases, monitoring
may be done by onfy one of the systems "to the extent that the interconnection of
the systems justifies treating them as a single system for monitoring purposes" (40
CFR 141.29).
                                  *•
      In many cases, States may require the bulk supplier to be responsible for
monitoring/treating the source water and the system(s) thatreceives the water to
be responsible for monitoring/maintaining the distribution system that carries the
water to the customers.  However, monitoring requirements for a Consecutive
Water System may vary rule-by-rule, if the State so decides.  If a State modifies
monitoring for these water systems, the State must provide a schedule detailing
the modified monitoring requirements, and EPA must concur with the schedule (40
CFR 141.29).

For more information about these topics:           Refer to these questions:

PWSs                 .                   I.2 -1.7 and I.9.

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1.9.   Does every EPA drinking water regulation apply to all types of Public
      Water Systems?

      No, each EPA drinking water regulation does not apply universally to all
PWSs. Each regulation specifies which type(s) of water systems must follow it.

      CWSs are  subject to all of EPA's drinking water  regulations, with the
possible exception of the Surface Water Treatment Rule, which only applies to
systems using surface water sources or ground water under the direct influence
of surface water. The Surface Water Treatment Rule protects consumers from the
adverse health effects of microbiological  contaminants in  drinking water by
requiring affected systems to disinfect and/or filter their source water. CWSs need
to comply with all  other federal drinking water regulations since these systems
serve residences where people consume water from the same water supply over
a long period of time, thus making them more vulnerable to long-term and  short-
term health effects from contaminants occurring in that drinking water.

      In general,  the regulations applying to CWSs  apply to NTNCs as well.
Water from NTNCs is not consumed by people as regularly over the long term as
is water supplied  by CWSs. Therefore,  NTNCs  do not have to follow all  of the
regulations that CWSs  do.  TNCs only have to follow a few regulations because
people may only consume water from these systems over  a very short period of
time.  Thus, Transient systems  only have to comply with contaminants such as
coliform bacteria, nitrates and nitrites, all of which can cause acute health effects.
See Appendix A for more information  on which  types and sizes of PWSs must
follow each regulation.

For more information about these topics:            Refer to these questions:

PWSs                                      1-2 -1.8, IH.B.5, IV.2 - IV.3 and IV.7 -
                                           IV. 12.

1.10.  What about household  or "private" wells?

      Household wells are not regulated under EPA's drinking water program and
are .generally regulated on a limited basis by the States.

      Household  wells that serve individual households, and  not  the general
public, are not regulated by EPA. To be a PWS, a minimum of 25 persons or 15
service connections must be served by a drinking water source. Household wells
are private property, and the owners are responsible for the quality of the water
taken from their individual wells. In rural areas, it is not uncommon to have wells
provide drinking water to restaurants, gift shops,  etc.  In this situation, depending
on the number of persons served, these wells may be considered to be  PWSs.
Local health departments may provide assistance to well owners whose wells are
not regulated as PWSs by EPA, e.g., testing for bacteria and nitrates,  but the "well
owner is primarily responsible for the  safety of water that  is  drawn from his/her
well" (Drinking Water from Household  Wells, p. 6).

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      As stated previously, however, States may regulate household wells. For
instance, some States  may  test or  require well  owners  to  test for certain
compounds.   Others may establish standards for the  size,  structure and/or
maintenance of private wells.  Some States may even regulate any well that has
at least two service connections as a PWS. The decision to regulate private wells,
as well as the extent of those regulations, lies solely with the State.  Therefore,
regulations on private or household wells will vary State-by-State.

For more information about these topics:            Refer to these questions:

EPA Enforcement/Authority                      1.1 and 1.11.


1.11.  How does EPA enforce its drinking water regulations?

      EPA enforces its drinking water regulations by using the authority provided
to the Agency in Section  1414 of the SDWA.  EPA may issue administrative orders
or file civil  actions against violators.  In addition, EPA may take action under
Section 1431 of the SDWA when there is or may be ah "imminent and substantial"
endangerment to health  (SDWA, Section 1431).  The Agency can also authorize
States, Indian Tribes and U.S. Territories to enforce drinking water regulations by
awarding them primary enforcement responsibility (primacy).

      The SDWA provided States, U.S. Territories and Indian Tribes the ability to
apply for and receive primary enforcement responsibility (primacy) for the drinking
water program.  When  primacy  is granted,  the States generally have the first
opportunity to  enforce the regulations.  EPA, then, acts when the State cannot or
does not act.  However, EPA retains the right to take action against any violator
at any time.

      Currently, 55 States and U.S. Territories have primacy.  In the continental
United States, only Wyoming and Washington, D.C. do  not have primacy.  No
Indian Tribes have attained primacy at this time. To obtain primacy, States or
Indian Tribes must adopt drinking water regulations at least as stringent as EPA's
requirements and  demonstrate to the Agency that they 'have  the capability to
enforce drinking water regulations (SDWA, Section 1413).  Specifically, States and
Indian Tribes must do the .following:

            •    Adopt and implement adequate procedures for enforcement;

            •    Keep records and make reports as required by EPA;

            •    Issue variances  and exemptions (if at all) which are no less
                  stringent than required by EPA and finally;

            •    Adopt and be able to implement an adequate emergency plan
                  to provide drinking water in the event of an  emergency such
                  as a flood, earthquake, hurricane, etc.  (Primacy Fact Sheet,
                  p. 2).

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      To maintain primacy, States must continue to adopt or.enact regulations at
least as stringent as each newly-promulgated federal regulation within 18 months
after EPA promulgates it, although a two-year extension may be granted by EPA
to a State on a case-by-case basis.  Once States enact drinking water regulations,
they must implement and enforce them, or EPA can withdraw primacy.  In some
cases, a State may have primacy for most drinking water regulations but may still
be in the process of attaining it for new federal regulations.  In that case,  EPA
would retain enforcement responsibility for the new regulations until that State
attained primacy for them.

      A State that has primacy generally takes the first enforcement action against
a PWS that fails to comply with all or part of a'drinking water regulation.  Once
EPA learns  of a violation, it informs  the water system and the State of the
violations) and provides advice or technical assistance. If the State has not begun
an appropriate enforcement action within 30 days of EPA's notice, the Agency may
step in and issue an administrative order to the system.  If the system  does not
comply with the administrative order, EPA may assess a penalty administratively
of up to $5,000; if EPA proceeded directly with a civil action for a violation (i.e.,
skipped the administrative order), the Agency may assess a penalty up to $25,000
per day every day that the PWS fails to comply (SDWA, Section 1414).

      The SDWA also gives EPA authority to act in the event of an "imminent and
substantial endangerment to the health of person" due to contaminated drinking
water  (SDWA, Section 1431).   For  example,  if a water  supply   becomes
contaminated with fecal coliform bacteria (or if there was a threat of potential future
contamination), EPA can step in and  require the  PWS to supply its users with
bottled water until the system removes the bacteria from its water.

For more information about these topics:            Refer to these questions:

EPA Enforcement/Authority                      l.i           ,           =

NPDWRs                                    11.1,  II.3, II.5 -11.10, 11.17, III.B.1 and IV.1


1.12.   Who  ensures the safety of materials  and contact surfaces used by
       drinking water systems?

       Public Water Systems use a broad range of chemical products to treat
water supplies and maintain storage and distribution systems. These products
are commonly referred to as drinking water additives, and they  include
coagulant aids, corrosion inhibitors, disinfectants, protective paints and
coatings, pipes and others. These products and associated impurities  require
scrutiny because they are a potentially significant source of contamination that
may adversely affect drinking water quality and public health.
 8

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      In the past, EPA assisted the States and PWSs on the use of additives
by issuing advisory opinions on the acceptability of many of these products.
The federal advisory program, however, ended on October 4, 1988. At that
time, EPA assisted NSF International in establishing voluntary product
standards.  This change in program is described in a Federal Register notice
(53 FR 25586, dated July 7, 1988).

      EPA recommends that all PWSs utilize NSF International Standards 60
and 61 when evaluating the acceptability of drinking water additives. For further
information on these standards, contact NSF International by writing to them at
P.O. Box 1468, 3475 Plymouth Road, Ann Arbor, Michigan 48106 or by calling
them at (313) 769-8010. For more information about private sector additives
programs, contact the American Water Works Association by writing to them at
6666 West Quincy Avenue, Denver, Colorado 80235, or by calling them at (303)
794-7711.

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                       Sources Cited in Section I


Code of Federal Regulations, Title 40 CFR 141. Government Printing Office. July
      1992. [40 CFR 141]


Federal Register. Vol. 53, No.  130.  Drinking Water  Technical  Assistance;
      Termination of the Federal Drinking Water Additives Program.  July 7, 1988.
      [53 FR].


U.S. Congress. Safe Drinking Water Act. 42 U.S.C. Section 300f et seq. June 1986.
      [SDWA, Section].


U.S. Environmental Protection Agency. Drinking Water from Household Wells (EPA
      570/9-90-013). September 1990. [Drinking Water from Household Wells].


U.S. Environmental  Protection  Agency. Fact Sheet: Revision  to State Primacy
       Regulations for the Public Water Supply Supervision (PWSS)  Program (No
       EPA Number).  December 1989. [Primacy Fact Sheet].
 U.S. Environmental Protection Agency. FY1993 National Compliance Report (EPA
    •  812/R-94-001). March 1994.  [Compliance Report].
 10

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       II.  Drinking Water Standard Components/Definitions
11.1.   What is a National Primary Drinking Water Regulation (NPDWR)?

      An  NPDWR is an enforceable standard that protects the quality of the
nation's drinking water.  These standards apply to PWSs and protect drinking
water quality by controlling the levels of specific contaminants that can adversely
affect public health and are known or anticipated to occur in water.  EPA may
establish a Maximum Contaminant Level (MCL) or a Treatment Technique (TT) as
an NPDWR for a contaminant. Both are discussed in more detail in this section.

      When developing NPDWRs for contaminants beyond the 83 listed  by
Congress  in the SDWA, EPA's Office of Water selects contaminants that are
judged to be threats to the nation's drinking water supplies in either raw or finished
water. EPA derives a Maximum Contaminant Level Goal (MCLG) and an MCL or
a TT for each drinking water contaminant the Agency has deemed to be a potential
threat  (SDWA, Section 1401).  TTs are established in  lieu of MCLs when a
contaminant cannot be measured accurately at levels of public health concern. As
part of each NPDWR, EPA also develops requirements for monitoring, treatment
technologies and analytical methods for each contaminant (SDWA, Section 1412).

For more information about these topics:            Refer to these questions:

MCLs                                      II.3 - II.4, II.6,  III.B.1, III.B.3 and III.B.6 -
                                          III.B.9.

MCLGs                                    II.2, II.4 and III.A.1 - III.A.3.

TTs                                        H.5 - II.6.
11.2.   What is a Maximum Contaminant Level Goal (MCLG)?

      An MCLG is the level of a contaminant in drinking water at which there is
no known or anticipated health threat from that contaminant to a person who
consumes the water. This nonenforceable health goal is defined as the "maximum
level of a contaminant in drinking water at which no known or anticipated adverse
effect on the health of persons would occur, and which allows an adequate margin
of safety" (SDWA, Section 1412(b)(4)).  Although non-enforceable, EPA publishes
contaminants' MCLGs and  associated  health effects in the Federal Register and
Code of Federal Regulations so that the public can easily note this information.
                                                                     11

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      For each contaminant selected for regulation, EPA first sets an MCLG that
is  based on that contaminant's health effects and exposure, both known  or
anticipated.  EPA determines each MCLG with an adequate margin of safety to
ensure that the contaminant can have no  adverse health effect on individuals
(SDWA, Section 1412(b)(4)). To determine this health-based goal, EPA conducts
a risk assessment,  examining data for cancer and/or non-cancer causing health
effects.  Under current EPA policy, when a contaminant is considered to  have
strong evidence of carcinogenicity from human and animal studies, the MCLG for
that contaminant is usually set at zero since scientists do not know if any level of
exposure, no matter how small, might cause cancer.  MCLGs are also set at zero
for other contaminants where exposure at  any level may cause adverse health
effects, e.g., for coliform bacteria.

For more information about these topics:            Refer to these questions:

MCLGs                                    H.4 and III.A.1 - III.A.12.


II.3.   What is a Maximum Contaminant Level (MCL)?

   An MCL is  the maximum  level of a contaminant that is allowable in public
drinking  water  supplies.   Congress  defined this term in the SDWA as the
"maximum permissible level of a contaminant in water  which is delivered to any
user of a public water system"  (SDWA, Section 1401 (3)). When EPA sets an MCL
for a contaminant, the PWS must ensure  that the level of this contaminant  is
maintained at or below its MCL.

      MCLs are enforceable  numerical limits that restrict the concentration  of
specific contaminants in the nation's drinking water. By law, EPA must set MCLs
and  MCLGs simultaneously. The SDWA also requires EPA to set each MCL as
close to that contaminant's  MCLG as is achievable for large PWSs, taking  costs
and feasibility of treatment into consideration (SDWA, Section 1401 (1)(C)(ii)). For
many noncarcinogenic contaminants,  the MCL and MCLG are the same, since it
is technologically  and economically  feasible to  maintain the levels of those
contaminants at the health-based level.

For more information about these topics:             Refer to these questions:

MCLs                                      II.1, HA II.6, III.B.1 - III.B.4, III.B.6 -
                                           III.B.10andlV.1.

11.4.   How is a Maximum  Contaminant Level Goal  (MCLG) different from a
      Maximum Contaminant Level (MCL)?

      An MCLG is a non-enforceable goal derived solely from health effects data.
An MCL is the  enforceable  level set as closely as possible to  the MCLG, taking
technological and cost data into account.
 12

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       As discussed previously, when EPA establishes an NPDWR, the Agency
 sets the MCL and the MCLG at the same time, and it must ensure that the MCL
 is as close to  the  MCLG as  is technologically feasible,  taking costs and  the
 feasibility of treatment into consideration (SDWA, Section 1412(a)(3)>.  Consistent
 with legislative history,  the  Agency  traditionally considers feasibility for large
 metropolitan and regional water systems in setting standards.

       If an MCL is exceeded by a PWS, then that system is in violation and must
 report to the State, notify the  public and take action to bring  the level of that
 contaminant at or below its MCL.  EPA and the States take actions on violations
 of regulations.  If a water system exceeds an MCLG of a contaminant without also
 exceeding its MCL, the water system will not be required to treat its water to lower
 the level of that contaminant.
For more information about these topics:

MCLs


MCLGs
Refer to these questions:

11.1, II.3, II.6 - II.7, III.B.1 - III.B.2 and
III.B.6 - III.B.10,

11.1 - II.2 and IILA.1 - III.A.3.
11.5.  What is a Treatment Technique (TT)?

      A TT is an enforceable procedure or set of procedures which PWSs must
follow to ensure that a contaminant is controlled in their drinking water supplies.
EPA is authorized to develop a TT for a contaminant when "it is not economically
or technologically feasible to ascertain the level of the contaminant" (SDWA,
Section 1412(b)(7)(A)).  Under a TT requirement, a PWS treats its water according
to EPA specifications (SDWA, Section 1412 (b)(7)(A)).

      For example, in the Lead and Copper Rule (56 FR 26460, dated June 7,
1991), EPA employs a TT to control the  amount of lead and copper in public water
supplies.  Since the majority of lead and copper contamination results from the
corrosion of household plumbing fixtures containing these metals, EPA requires
PWSs to monitor at selected taps rather than at the entry point to the distribution
system. However, the Agency did not set an enforceable MCL for samples at the
tap because the composition of household plumbing is not in the control of PWSs.
Therefore, EPA established a TT, which among  other things, requires PWSs to
control the corrosivity of their water.  Corrosion is defined as a dissolving and
wearing away of metal caused by a chemical reaction between the water and the
lead/copper in the pipes. Corrosivity, then, is the measure of how much metal is
likely to dissolve or  wear away into the water.  Corrosion control  treatment will
inhibit the leaching  of  lead and copper from  household  plumbing and lead
distribution lines caused by corrosive water.
                                                                       13

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      The Surface Water Treatment Rule is another example of a TT. This rule
applies to all PWSs that use surface water or ground water under the direct
influence of surface water.  These systems must disinfect and either filter their
water or meet EPA's requirements for avoiding filtration in order to protect their
water "against the potential adverse health effects of exposure to Giardia lamblia,
viruses, Legionella and heterotrophic bacteria, as well as many other pathogenic
organisms that are removed by [the Surface Water Treatment Rule requirements]"
(54 FR 27487).
For more Information about these topics:

TTs
                                          Refer to these questions:

                                          11.1 and 11.6 - 11.7.
11.6.  How do an MCL and a Treatment Technique differ?

      An MCL establishes a level that a PWS must maintain for a contaminant,
while still allowing the PWS flexibility in determining how to meet the numerical
standard. A TT specifies procedures a PWS must do to treat a contaminant in its
water.
      While both  MCLs and .TTs are  enforceable standards,  an MCL is a
numerical limit that a PWS must remain at or below in order to comply with EPA's
regulations.    Although  EPA designates treatment  technologies,  called  Best
Available Technologies (BATs), that can lower the level of a contaminant at or
below its MCL, the Agency does not require PWSs to use BATs to treat their water.
Instead, a water system may use any means to lower a contaminant level as long
as it allows the system to comply with an MCL

      On the other hand, a TT is a treatment procedure, or series of procedures,
that a PWS must follow  to comply with a drinking water regulation.   EPA
establishes a TT to regulate a contaminant (instead of setting an MCL for it) only
when it is not feasible to ascertain the level  of a contaminant (SDWA, Section
1401
                                          Refer to these questions:

                                          H.1, H.3 - 1 1. 4, IH.B.1 - III.B.3, III.B.6
                                          III.B.10 and IV.1.

                                          11.1, II.5 and II.7.
For more information about these topics:

MCLs


TTs
11.7.   How many National Primary Drinking Water Regulations  (NPDWRs)
       have been promulgated?

       Currently, EPA has promulgated NPDWRs for 84 contaminants.  The
Agency  has proposed regulations  for additional contaminants, and it has
scheduled several other contaminants for proposal in the future. A list of the 84
currently regulated contaminants, with each one's MCLG, MCL/TT and potential
health effects, is included in Appendix Bs Table 1 .
 14

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       In  1986,  when  the  SDWA was reauthorized,  Congress  mandated 83
contaminants for EPA to regulate, allowing EPA to replace compounds from the
mandated list with other contaminants if necessary. Out of that list of 83,  EPA
regulated 76 contaminants including 7 contaminants that had replaced compounds
on the list. The Agency also regulated one contaminant (dibromochloropropane)
independent of the 1986 mandate.  Seven contaminants (out of the 84 that are
currently promulgated) were promulgated before the 1986 amendments to the
SDWA. EPA still has to regulate radon, uranium and sulfate from the list as well
as revise its regulations for radium, gross alpha emitters, beta/photon emitters and
arsenic.

       When developing  NPDWRs for contaminants beyond  the  83 listed by
Congress in the SDWA, EPA goes through a rulemaking process, which begins by
choosing  contaminants for the Drinking Water Priority List (DWPL) based on
preliminary occurrence and health effects data.  Some contaminants "are placed
on the list because they clearly present a health risk; others will require further
investigation before the need for regulation is clear" (56 FR 1471). Once EPA has
developed the DWPL, the Agency then further examines the health effects  and
occurrence  data for  those chosen contaminants,  proposes  to  regulate  the
contaminants that occur or have the potential to occur in drinking water at levels
that  may  cause health effects,  takes and reviews public comments  on  the
proposed regulations  and  finally,  promulgates  or  finalizes the  proposed
contaminants.

       Except for some of the 83 contaminants specified in the SDWA, EPA  has
promulgated regulations for contaminants that have been found to be prevalent in
many or most drinking water supplies nationally and that may  have an adverse
health  effect on persons.  Currently,  EPA has developed NPDWRs for synthetic
organic compounds  (SOCs), volatile  organic  compounds (VOCs),  inorganic
compounds  (lOCs), some radionuclides and microorganisms.   SOCs are man-
made chemicals such as pesticides and industrial chemicals. VOCs are naturally-
occurring  or man-made volatile chemicals that can move easily from water to air.
Most VOCs are industrial chemicals.  lOCs are metals and minerals that can occur
naturally or  be  introduced by human activity  into drinking  water  supplies.
Radionuclides are radioactive contaminants that can also occur naturally or as a
result of human activity. These contaminants can pose either a short-term or a
long-term  health risk.   EPA also regulates disease-causing microorganisms in
drinking water.  Microorganisms regulated by EPA include bacteria, viruses and
protozoa, all of which can pose short-term or acute health risks to a PWS's users.

For more information about these topics:           Refer to these questions:

Number of NPDWRs                          II.8 -11.12 and 111.17.
                                                                     15

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11.8.   How many of these standards are now effective?

      All 84 are currently effective.  Regulations for the contaminants currently in
effect are presented in Appendix B, Table 1.  Table 2 lists the dates they became
effective.

      The SDWA normally establishes an 18-month period between the time an
MCL or TT is promulgated and the time that the regulation becomes effective: This
means that when EPA regulates a contaminant, PWSs normally have 18 months
from that promulgation date before they  must begin controlling its level in the
drinking water they supply consumers.  Due to the lag between the effective date
of a final rule and the date that a State with primary enforcement responsibility
adopts a final rule, enforcement of a new final rule may be the responsibility of the
EPA until a State attains primacy for it.

For more information about these topics:            Refer to these questions:

Number of NPDWRs                            II.7, II.9-11.12 and 11.17.
11.9.  When would there be fewer standards effective than final?

      As discussed above, under the SDWA there is a period of 18 months before
a final rule becomes effective.  For 18 months after a rule has been finalized, those
contaminants regulated under that rule will be final but not yet effective. Systems
may choose to or may be required to monitor for the contaminant before an MCL
becomes effective.  If the results of that monitoring show that  a system exceeds
an MCL, the PWS has time to come into compliance before the rule is effective and
a violation would be incurred. Appendix B, Table 1  presents a  listing of regulated
contaminants by rule while Appendix B, Table 2 lists the effective date for each
rule.

      When EPA promulgates an NPDWR, States with  primacy have 18 months
from that promulgation date to revise their primacy programs and adopt the new
rule (SDWA, Section 1412(b)(10)).   Some  States have been  granted extension
agreements for up to two years to adopt final regulations  promulgated  by EPA.
States must adopt regulations no less stringent than the federal regulations, and
they must be able to demonstrate to EPA that they have the capability to enforce
such regulations  (SDWA,  Section 1413(a)).   This 18-month period serves three
purposes:  (1) It allows the States to adopt the regulation so  that they can maintain
primacy; (2) It allows EPA and/or the States to certify laboratories to test for that
contaminant; and (3) It allows time for PWSs to comply with the regulation.

For more information about these topics:            Refer to these questions:

Number of NPDWRs                           H-7 -11.8, 11.10  -11.12 and 11.17.
 16

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 11.10.  How many NPDWRs are currently proposed but are not yet final?

       At this time, EPA has proposed NPDWRs for 20 contaminants either singly
 or as  a contaminant group  (such as haloacetic acids) that have not yet been
 promulgated.  Six of these contaminants are radionuclides, which were proposed
 on July 18, 1991 (56 FR 33050).  Twelve of these contaminants are disinfectants
 or disinfection byproducts (D/DBPs), which were proposed on July 29, 1994 (59
 FR 38668).  The  Enhanced Surface  Water Treatment Rule,  which regulates
 Cryptosporidium, was also proposed on July 29,1994 (59 FR 38832). The Sulfate
 Rule was proposed in December 1994.

       When EPA proposes a regulation, the Agency lists the contaminants that it
 plans  to regulate  along  with the proposed MCL  or TT requirement for each
 contaminant.  EPA also lists monitoring, reporting and any special State primacy
 requirements  in the proposed rule.  EPA has proposed  regulations  for six
 radionuclides: adjusted gross alpha emitters, beta particle and photon emitters,
 radium-226, radium-228,  radon-222  and  uranium.  Some of these compounds,
 such as radon-222 and uranium,  have never been regulated in drinking water by
 EPA.   Some  compounds, such as radium-226 and radium-228,  are  already
 regulated, and EPA is proposing to  revise their levels.  EPA has also proposed
 regulations for 12 D/DBPs, including chlorine, chlorine dioxide, chloramines,
 chlorite, bromate, haloacetic acids (a group of five) and total trihalomethanes (a
 group  of four). The Enhanced Surface Water Treatment Rule will revise/update
 some  of the Surface Water Treatment Rule requirements  as  well as regulate
 Cryptosporidium.  Last, EPA proposed to regulate sulfate as a  National Primary
 Drinking Water Regulation (NPDWR)

       In a proposed regulation, EPA  may  specify the date that  it expects to
 promulgate the proposed rule.  However, there is no guarantee that the Agency
 will finalize a rule exactly as it was proposed.  In some instances, EPA may
 promulgate a contaminant at a different level than it was proposed, or the Agency
 may decide to not promulgate it at all.

 For more information about these topics:           Refer to these questions:

 Number of NPDWRs                           H.7 - II.9, 11.11 -11.12  and 11.17.

 11.11.  Will any primary drinking water regulations be proposed or finalized
      in the future?

      Yes, EPA plans to  propose regulations for several contaminants, such as
 arsenic and aldicarbs.  EPA  also plans to propose the  Phase Vl-b Rule, which
would promulgate MCLs for multiple contaminants. In addition, the Agency plans
to propose additional TT requirements  for  pathogens (the Ground  Water
 Disinfection Rule).

      At this  time,  EPA is subject to  court-ordered  deadlines to propose
regulations for the disinfection  of ground water by August  1995, with the final
regulations expected in August  1997. The Agency also plans to repropose the

                                                    !                  17

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standards for aldicarb, aldicarb sulfone and aldicarb sulfoxide in Fiscal Year 1995.
EPA is under a court-ordered deadline to propose a revised rule for arsenic in
November 1995 and finalize it two years later.  The Agency is also under a court-
ordered deadline for the Phase Vl-b Rule, which will set standards for selected
organic and inorganic contaminants in drinking water.  Under this court-ordered
deadline, EPA has to propose the Phase Vl-b Rule in  February  1995 and
promulgate it in February 1997.

For more information about these topics:            Refer to these questions:

Number of NPDWRs                           II.7 -11.10,11.12 and 11.17.


11.12. Does EPA  have a  list of what contaminants will be  proposed  or
      finalized in the future?

      Yes, as required by the SDWA, EPA prepares the Drinking Water Priority List
(DWPL)  every three years.  This list  names  the  contaminants that EPA is
considering for future regulation.  However, EPA will not necessarily regulate every
contaminant on the DWPL                                    ;

      The  DWPL  is a list  of contaminants that may occur in  drinking water
supplies and that may require regulation under the SDWA, as amended in 1986
(SDWA, Section 1412(b)(3)(A)). As discussed previously, the SDWA requires EPA
to propose and promulgate standards for at least 25 contaminants every three
years.  EPA uses  the DWPL  as a source for identifying new contaminants to
regulate.  EPA published the first list of 53 contaminants on January 22, 1988 (53
FR 1892), fulfilling the requirements in the SDWA Amendments of 1986 (56 FR
1470).  EPA published the latest edition of the DWPL on January 14, 1991 (56 FR
1470) (See Appendix C). At this time, only the D/DBPs and Cryptosporidium has
been proposed from the most recent DWPL. No other contaminants listed on the
most current DWPL have been proposed or promulgated; however, EPA is under
a  court-ordered deadline  to  propose  the  Phase Vl-b Rule, which includes
contaminants from  the most recent DWPL, by February 28, 1995.

      EPA  is under  a court-ordered  deadline to propose regulations  for
disinfecting ground water by August 30, 1995.  The Phase Vl-b Rule, which will be
comprised of contaminants that the Agency judges to cause potential health
concerns in drinking water, has been scheduled for proposal by February 28,
1995.

For more information about these topics:            Refer to these questions:

DWPL                                     11.13 -11.15.
18

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11.13. Do the contaminants on the Drinking Water Priority List (DWPL) have
      MCLGs and MCLs?
      No, the DWPL does not include MCLs or MCLGs.
compounds that may be regulated by EPA in the future.
             It is merely a list of
      EPA places contaminants on the DWPL based on preliminary occurrence
and health  effects  information.   No  MCLs  or MCLGs are established  for
contaminants on  the basis of such preliminary information. However, from the
DWPL, EPA is required to propose regulations for at least 25 contaminants (SDWA,
Section 1412(b)(3)(C)). EPA is also required to promulgate regulations for at least
25 contaminants; each promulgated compound would then have a final MCLG and
MCL or TT. (SDWA, Section 1412(b)(3)(D)).
For more information about these topics:

DWPL

MCLGs

MCLs
Refer to these questions:

11.12 and 11.14-11.15.

II.2, II.4, III.A.1 -III.A.3and IV.1.

II.3 - II.4, II.6, 11.19, III.B.1 -III.B.3, III.B.6
lil.B.Tand III.B.9 - III.B.10.
11.14. How does EPA choose which contaminants to place on the Drinking
      Water Priority List (DWPL)?

      EPA chooses contaminants for inclusion on the DWPL from a variety of
sources based on preliminary data focusing on occurrence and health effects of
each contaminant.

      To make this determination, EPA forms a workgroup composed of members
from the National Toxicology Program and members of EPA from the Office of
Science and Technology and the Office of Ground Water and Drinking Water (both
are in the Office of Water); as well as from the Offices of Prevention, Pesticides and
Toxic Substances; Solid Waste and Emergency Response and other appropriate
offices.   In  addition  to  other sources, the SDWA requires EPA to consider
contaminants listed in  Section 101(14) of the Comprehensive Environmental
Response, Compensation and Liability Act (CERCLA) of 1980, and substances in
the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) when selecting
candidates  for inclusion in the DWPL  (SDWA,  Section 1412(b)(3)(B)).   EPA
identifies contaminants for  inclusion based on some level of potential  health
concern and some likelihood of occurrence in public drinking water supplies.
For more information about these topics:

DWPL
Refer to these questions:

11.12 -11.13 and 11.15.
                                                                     19

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11.15.  Is the DWPL ever revised?

      Yes, as discussed in Questions 11.12 through 11.14, EPA must revise the
DWPL every three years as required by the SDWA Amendments of 1986.

      The latest DWPL, published in the Federal Register on January 14, 1991,
contains 77 contaminants (56 FR 1470). In this revised list, EPA carried over 50
contaminants from the previous DWPL of 1988 (53 FR 1892) and added 27 new
contaminants (56 FR 1470).

For more information about these topics:           Refer to these questions:

DWPL                                      11.12-11.14.


11.16.  Are promulgated standards ever revised?

      Yes, EPA revises promulgated standards. If EPA determines that changes
to a regulation will  provide greater protection to human health,  then EPA will
propose and then promulgate a revised regulation.

      EPA has revised several  of its  standards, including those  for barium,
cadmium, lead, nitrate,  selenium, silver,  lindane, mercury and chromium,,among
others.  The Total Coliform Rule was revised in June of 1989,  and  the Surface
Water Treatment Rule  may be  revised/updated in the  future  if  the proposed
Enhanced Surface Water Treatment Rule (which was proposed July  29, 1994) is
promulgated.  EPA is under a court-ordered deadline to propose revisions to the
Arsenic Rule by November 1995.

For more information about these topics:           Refer to these questions:

NPDWRs                                   N-1, H.3, II.5  -11.12, III.B.1,  IV.1, IV.7 -
                                          IV.8andlV.11.

11.17.  What is a Secondary Drinking Water Regulation (SDWR)?

      An SDWR is a non-enforceable guideline regarding cosmetic effects (such
as skin or tooth discoloration) and aesthetic effects (such as its  taste, odor or
color) of drinking water. EPA recommends them to water systems but does not
require systems to comply with these secondary, or aesthetic-based, levels.

      EPA recommends SDWRs for contaminants that do not cause adverse
health affects, but instead, adversely affect the cosmetic  or aesthetic qualities of
drinking water.  However, States may choose to adopt  SDWRs as  enforceable
standards. In some cases, a contaminant may have a primary and a secondary
drinking water standard.  This simply means that at certain levels  a contaminant
may adversely affect the cosmetic or aesthetic quality of drinking water while at
higher levels  the same contaminant may adversely affect the public health. An
example of this is fluoride, which at levels above 4 mg/l may cause skeletal
20

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damage. However, at levels between 4 mg/l and 2 mg/l, fluoride may only cause
a brownish discoloration of the teeth, called dental fluorosis, which EPA currently
considers to be an aesthetic concern. Therefore, EPA set a primary, health based,
MCL of 4 mg/l and a secondary, cosmetic based, SMCL of 2 mg/l for fluoride.
For more information about these topics:

SDWRs
Refer to these questions:

11.18.
11.18. How  is  a National Primary  Drinking Water Regulation  (NPDWR)
      different from a Secondary Drinking Water Regulation (SDWR)?

      EPA sets NPDWRs  for contaminants  at levels that can adversely affect
public health. EPA sets SDWRs for contaminants at levels that can adversely affect
the aesthetic quality of drinking water.  NPDWRs are federally enforceable; SDWRs
are not.

      NPDWRs are enforceable standards to which PWSs must adhere to stay in
compliance with the Safe  Drinking Water Act.  SDWRs are non-enforceable
standards on the federal level. A PWS would not have to follow these standards
unless its State  had adopted them as enforceable State regulations.  In  addition,
NPDWRs are uniform for the nation,  while SDWRs may  have ranges or vary
according to geographic or source water characteristics (such as aluminum and
PH).
For more information about these topics:

NPDWRs


SDWRs
Refer to these questions:

11.1, II.3, II.5 -11.12. III.B.1, IV.1, IV.7
IV.Sand IV.11.

11.17.
                                                                      21

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                       Sources Cited in Section II.
Code of Federal Regulations, Title 40 CFR 141. Government Printing Office. July
      1993. [40 CFR 141]

Federal Register. Vol. 53, No. 14. Drinking Water; Substitution of Contaminants and
      Drinking Water  Priority List of Additional Substances Which May Require
      Regulation Under the Safe  Drinking Water Act. January 22, 1988. [53 FR].

Federal Register. Vol.  56, No. 9.  Priority  List of Substances Which May Require
      Regulation Under the Safe Drinking Water Act; Notice. January 14, 1991.
      [56 FR].

Federal Register. Vol.  56, No. 20. National Primary Drinking Water Regulations;
      Final Rule. January 30, 1991. [56 FR].

Federal Register. Vol. 56,  No. 110. Maximum  Contaminant Level  Goals and
      National Primary Drinking Water Regulations for Lead and Copper;  Final
      Rule. June?, 1991. [56 FR].

Federal Register. Vol.  56, No.  138. National Primary Drinking Water Regulations;
      Radionuclides; Proposed Rule. July 18, 1991.  [56 FR].

Federal Register. Vol.  58, No. 78. National Primary Drinking Water Regulations;
      Notice of Proposed Rulemaking. April 26, 1993. [58 FR].

Federal Register. Vol.  59, No.  145. National Primary Drinking Water Regulations:
      Enhanced Surface Water Treatment Requirements; Proposed Rule. July 29,
      1994. [59 FR].

Federal Register. Vol.  59, No. 145. National Primary Drinking Water Regulations;
      Disinfectants and Disinfection Byproducts; Proposed Rule. July 29, 1994.
      [59 FR].

U.S. Congress. Safe Drinking Water Act. 42 U.S.C. Section 300f et seq. June 1986.
      [SDWA].

U.S. Environmental Protection Agency.  EPA Fact Sheet: Fluoride in Drinking Water
      (EPA 822/F-93-010). December 1993. [Fluoride Fact Sheet].
22

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  III. Maximum Contaminant Level Goals (MCLGs) and Maximum
                     Contaminant Levels (MCLs)
                             III.A. MCLGs

III.A.1.       How does EPA  set a  Maximum Contaminant  Level Goal
             (MCLG)?

      EPA sets an MCLG for each regulated contaminant at a level where no
known or anticipated health risk will occur and which allows an adequate margin
of safety (SDWA, Section 1412(b)(4)).  EPA's Office of Science and Technology
(OST) (in the Office of Water) places each contaminant (with the exception of
microorganisms and indicator bacteria, which are examined for waterborne disease
potential) into one of three categories: Category I - indicating strong evidence of
carcinogenicity, Category II - indicating limited evidence of carcinogenicity  and
Category III - indicating inadequate or no evidence of carcinogenicity based on
toxicity studies.

      The  specific procedure for setting an MCLG varies, depending on the
category to  which a  contaminant  is assigned.   For contaminants placed in
Category I, indicating strong evidence of carcinogenicity, EPA sets an  MCLG of
zero since EPA assumes that any exposure, regardless of how small, will increase
the risk of cancer (i.e.,  any dose will  increase  the risk of cancer).   For each
contaminant placed in Category II, EPA sets the MCLG by deriving its  reference
dose (i.e., the lowest daily level of a contaminant that will not produce non-cancer
adverse health effects) with  an additional margin of safety (57 FR 31781-31782).
For each contaminant placed in Category III, EPA sets the MCLG solely from the
reference dose. For all microorganisms, viruses, and coliforim bacteria, which are
not assigned to a category,  EPA sets an MCLG of zero.
For more information about these topics:

Cancer groups

Categories

MCLGs
Refer to these questions:

III.A.5 - III.A.6.

III.A.3 - III.A.4 and III.A.6 -III.A.7.

II.2. 11.4, III.A.7 - III.A. 12.
IH.A.2.      What is EPA's reasoning for setting MCLGs of zero?

      EPA sets  MCLGs of zero for contaminants that are known or probable
carcinogens since scientists do not know if any level of exposure, no matter how
small, might cause cancer.

      The SDWA requires EPA to set an MCLG for each contaminant at a level
where there is no known  or anticipated public health risk from ingesting that
contaminant in drinking  water.  As stated above, there  is no known level for
carcinogens that is protective of human health over a lifetime. Therefore, EPA sets
MCLGs of zero for substances considered to be known or probable human
                                                                     23

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carcinogens (i.e., for Category I  chemicals).  For pathogens and conforms the
health risks are acute; therefore, these organisms are also given an MCLG of zero
and the MCL (or TT requirements) are established to be protective of acute human
health risks.

For more information about these topics:            Refer to these questions:

Categories                                   III.A.3 and III.A.6.

MCLGs                                      11.2, 11.4, III.A.1 - III.A.3.

III.A.3.      When setting the MCLG, what are Categories I,  II and III, and
            how do these categories affect the MCLG setting process?

      Using data from long-term animal and human epidemiological studies,
EPA has established an  approach for setting MCLGs that involves placing each
regulated contaminant (except microorganisms, which currently are given an
MCLG of zero) into one  of three categories: Category I, Category II or
Category III.  Factors such as weight of evidence for carcinogenicity, cancer
potency, exposure, pharmacokinetics and mechanism of action influence the
category in which a contaminant is placed (57 FR 31782).

      Each category reflects a contaminant's  potential level of carcinogenicity
for humans who ingest it via their drinking water.  Category  I reflects strong
evidence of carcinogenicity, while Category II reflects limited evidence, and
Category 111 has inadequate or no evidence of carcinogenicity. As discussed
previously, EPA will derive an MCLG depending on the category in which a
contaminant has been placed. These categories and MCLG setting approaches
are summarized below:

                      EPA's Three-Category Approach
                          for Establishing MCLGs

                   Evidence of
                   Carcinogenicity
   Category        via  Inqestion                   MCLG Setting Approach

      I            Strong human or animal
                   evidence considering the        Zero
                   weight of evidence,
                   pharmacokinetics, and
                   exposure

      II            Limited animal  evidence         Reference  Dose (RfD)
                   considering weight             approach with added
                   of evidence, pharmaco-         safety margin or 10"5
                   kinetics, and exposure          to 10~6 cancer risk range           jji^

      III           Inadequate or no               RfD approach
                   animal evidence
24

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       In general, EPA has determined that for Category I contaminants, there is
 strong evidence of carcinogenicity from human or animal sjtudies.  It is current
 EPA policy that MCLGs for these contaminants be set at zero because it is
 assumed, in the absence of other data, that there is no known exposure
 threshold for carcinogenicity via ingestion in drinking water for these
 contaminants.

       EPA places contaminants for which there is  limited information of
 carcinogenicity from the weight of evidence, pharmacokinetics and exposure in
 Category II.  To establish an MCLG for a Category II chemical, EPA can use
 one of two approaches.  In the first, the Agency determines a contaminant's
 Reference Dose (RfD) by examining noncarcinogenic health effects and then
 dividing that  number by an additional margin of safely of 1  to 10.  In the
 absence of valid noncarcinogenic health effect information, however, EPA can
 set the MCLG based  on a theoretical lifetime excess cancer risk range of 10"5 to
 10'6 using a conservative mathematical extrapolation model (57 FR 31783)
 Typically, EPA uses the first approach.

       The last category, Category III, includes contaminants for which EPA has
 inadequate or no animal evidence of carcinogenicity via ingestion.  For these
 contaminants, EPA sets the MCLG by deriving the RfD using data  on
 noncarcinogenic health effects. However, the Agency does not apply a safety
 margin for carcinogenicity of 1 to 10 to these contaminant levels as it does for
 compounds in Category II.

 For more information about these topics:            Refer to these questions:

 Cancer Groups                                IH.A.4 - III.A.6.

 Categories                                   m.Al and m A6 .

 RfDs                                        III.A.8-IIIA11.
III.A.4.      What is a cancer classification?

      EPA has developed cancer classifications for chemicals according to their
possible carcinogenicity in humans.  The objective of this classification system is
to assess each contaminant in order to determine the level or strength of evidence
that the substance is a human or animal carcinogen (57 FR 31782).

      EPA's  cancer  classification  is  a system  for  evaluating the potential
carcinogenicity  of a regulated  contaminant.  There  are 5 groups  under this
approach (Groups A, B, C, D and E), with Groups A  and E? generally placed in
Category I, Group C placed in Category II and Groups D and E placed in Category
                                                                       25

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III.  While not intended to be applied rigidly or mechanically, this classification
system establishes guidelines for categorizing the weight of human and animal
evidence to determine the  potential  public health  risks from  cancer causing
contaminants.

For more information about these topics:             Refer to these questions:

Cancer Classifications                           III.A.5 - III.A.6.

III.A.5.       How many cancer classifications exist, and what does each
             classification mean?

      There are five  cancer classifications.   EPA evaluates  each  regulated
contaminant using data from human epidemiological or laboratory animal studies
and  classifies each according to its potential  carcinogenicity.   EPA is currently
revising this approach and has issued draft guidelines, but the current scheme will
be in effect until the revised guidelines have  been finalized.  The classification
scheme is included as follows:


      Group A:          Known human carcinogen based on sufficient evidence
                         from epidemiological or other human evidence studies.

      Group B1:         Probable human carcinogen based on limited evidence
                         of carcinogenicity in humans.

      Group B2:         Probable  human   carcinogen based   on  sufficient
                         evidence  in animals  and inadequate or no data in
                         humans.

      Group C:          Possible human carcinogen based on limited evidence
                         of carcinogenicity in animals in the absence of human
                         data.              ,

      Group D:          Not classifiable as to human carcinogenicity based on
                         lack of data or inadequate evidence of carcinogenicity
                         from animal data.

       Group E:          No evidence of carcinogenicity from  at  least  two
                         reliable tests in different species of laboratory animals
                         (51 FR  34000).

 For more information about these topics:            Refer to these questions:

 Cancer Classifications                          IH-A.4 and III.A.6.
 26

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III.A.6.      How does EPA determine which cancer classification to assign
            to a contaminant?

      EPA assigns a cancer classification to each contaminant by using data from
human and laboratory animal studies.

      EPA's Office of  Science and Technology (OST)  (in the Office of Water)
evaluates each'chemical contaminant's potential carcinogenicity via ingestion in
drinking water using data from human and laboratory animal studies and places
each compound into its appropriate cancer classification group. The Cancer Risk
Assessment  Verification  Endeavor (CRAVE),  a  workgroup  made  up  of
representatives  from various  EPA programs,  then reviews OST's decisions
regarding these cancer classifications (56 FR 3531).

For more information about these topics:      Refer to these questions:

Cancer Groups                         III-A.4 - III.A.5.
Categories                            '"-A.1. and III.A.3.
 III.A.7.      What is a cancer risk range, and how is it derived?

       The cancer risk range is an estimate of the probability that  a person.will
 develop cancer  after a lifetime  of  ingesting water  containing the  regulated
 contaminant.  There are several mathematical models that EPA can  use to derive
 this risk range using data from  human epidemiological or laboratory animals
 studies.

       The cancer risk range is a numeric criterion that the Agency derives in order
 to identify the level of exposure to a carcinogenic contaminant that will result in a
 lifetime risk of no greater than 10* to 10"6.  This means that it is a way to arrive at
 a numeric level that would be protective of the public so tnat no more than 1 in
 every 100,000 to 1  in every 1  million people would be at risk of developing cancer
 after ingesting that contaminant in their drinking water over their lifetimes.

       As discussed above, there are several mathematical models  that EPA can
 use to determine this risk range.  According to the Agency's Final Guidelines for
 Determining Carcinogen Risk Assessment, which appeared in the Federal Register
 on September 24,  1986, "No single mathematical procedure is recognized as the
 most appropriate for low-dose extrapolation in carcinogenesis"  (51 FR 33997).
 However, in most cases, EPA will use a procedure which incorporates low-dose
 linearity to calculate the cancer risk range (51 FR 33997).

 For more information about these topics:            Refer to these questions:

 Categories                                   HI-A.1 and III.A.3.

                                            III.A.8-III.A.11.
                                                                         27

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 III.A.8.
What are the NOAEL/LOAEL levels, and how are the levels
derived?
       NOAEL stands for no-observed-adverse-effect-level and LOAEL stands for
 the lowest-observed-adverse-effect-level. The EPA RfD Workgroup identifies both
 of these levels from human and laboratory animal  studies and uses either the
 NOAEL or the LOAEL to derive an  RfD.

       The NOAEL is a dose in a toxicity test that does not produce an observable
 adverse effect. The LOAEL is the lowest dose in a toxicity test that produces an
 observable adverse effect.  EPA derives the NOAEL  and the LOAEL from studies
 in  humans or laboratory  animals  (57  FR 31783).   In order  to calculate  a
 contaminant's RfD, EPA divides  the  NOAEL  or  LOAEL by  an appropriate
 uncertainty factor.
 For more information about these topics:

 NOAEL/LOAEL

 RfDs
                             Refer to these questions:

                             III.A.9.

                             III.A.9-III.A.11.
 III.A.9.      What is an uncertainty factor, and how is it derived?

       Uncertainty factors account for intraspecies and interspecies variations, for
 limited or incomplete data, for evaluating the significance of adverse effects and for
 pharmacokinetic factors (56 FR 3532). In other words, the uncertainty factor takes
 into account the differences in response to toxicity for a given contaminant within
 human and animal populations and between humans and animals,  as well as the
 quality of the data base and the type of toxicological effects (56 FR 3532).

       EPA has established the following criteria for determining the magnitude of
 the uncertainty factor (56 FR 3532).
       Uncertainty Factor

             1 -10


             100
            100
                       Criteria

                       When a NOAEL from a human study is
                       used to account for intraspecies diversity.

                       When a LOAEL from a human study is
                       used, incorporating  a factor  of  10 to
                       account for lack of a NOAEL and a factor
                       of 10 for intraspecies diversity.

                       When a NOAEL from an animal study is
                       used, incorporating  a factor  of  10 to
                       account for interspecies diversity and a
                       factor of 10 for intraspecies diversity.
28

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             1,000
             1-10
             other




 For more information about these topics:

 NOAEL/LOAEL

 RfDs
When a LOAEL from an animal study is
used, incorporating factors of 10 each for
lack of NOAEL, interspecies diversity and
intraspecies diversity.

Additional  uncertainty  factors,  ranging
from 1 to 10, may be incorporated on a
case-by-case  basis  to  account   for
deficiencies in the database.

Other uncertainty factors may be used
according to scientific judgment when
justified.

      Refer to these questions:

      III.A.8 and III.A.10.

      ill.A.8and III.A.10 - III.A.11.
 III.A.10.     What is a Reference Dose (RfD), and how does EPA determine
             it?
                                             f
       An RfD is  a  numeric level that estimates  the lowest daily level  of  a
 contaminant that will not produce adverse health effects.  This dose incorporates
 a margin of safety and protects sensitive members of the population. Although
 Category I contaminants (which are given an MCLG of zero) may have RfDs, EPA
 does not use the RfD to set the MCLG for these contaminants.  The Agency'uses
 the RfD to calculate the MCLG for Category II and III contaminants. The EPA RfD
 Workgroup derives an RfD level by determining either the no-observed-adverse-
 effect-level  (NOAEL) or the lowest-observed-adverse-effect-level (LOAEL) for  a
 contaminant and dividing that level by an uncertainty factor..

       The  RfD  is  defined  as an estimate "of a daily exposure to the human
 population  (including  sensitive  subgroups)  that is likely  to be  without an
 appreciable risk of deleterious health effects during a lifetime"  (57 FR 31783). The
 first step EPA performs to derive this level is to identify a contaminant's NOAEL or
 LOAEL that has been elicited from an appropriate scientific study of humans or
 laboratory animals.  Then, the Agency will divide the NOAEL or  LOAEL by an
 uncertainty factor.

       An uncertainty factor is used  to account for differences in response to
toxicity within the human population and between humans and laboratory animals,
and to evaluate the significance of those different responses, as well as to account
for limited or incomplete data. The Agency usually bases an RfD on a 70 kg
                                                                       29

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(approximately 154 pounds) adult who consumes an average of 2 liters of water
per day over a lifetime of 70 years.

      The mathematical formula for the calculation of the RfD is as follows (56 FR
3532):

        RfD =             NOAEL or LOAEL
      (mg/kg/d)
                          Uncertainty Factor
      Once it derives an RfD for a contaminant, EPA uses that numerical level,
expressed in milligrams per kilograms per day, to calculate a Drinking Water
Equivalent Level (DWEL) for that contaminant. EPA uses the DWEL to determine
an MCLG for a Category II or Category III contaminant.

For more information about these topics:           Refer to these questions:

Categories                                  III.A.1 and III.A.3.

NOAEL/LOAEL                              III.A.9 - III.A.10.

RfDs                                      IIIA8 - III.A.9 and IM.A.11.
HI.A.11.     What is a Drinking Water Equivalent Level (DWEL), and how is
            it derived?

      A DWEL is a lifetime exposure concentration of a contaminant in drinking
water that will not cause adverse, non-cancer health effects. This concentration
level assumes that all of a person's possible exposure to a contaminant comes
from a drinking water source.   EPA derives the DWEL  for  a contaminant by
multiplying the RfD by the weight of an adult (usually assumed to be 70 kilograms
or 154 pounds), and then dividing that number by the amount of water consumed
each day (usually assumed to be one liter per day for VOCs and two liters per day
for all other contaminants).
30

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       EPA defines the DWEL as the estimated exposure (measured in mg/l) which
 is protective for noncarcinogenic endpoints of toxicity over a lifetime of exposure.
 The DWEL assumes that the total daily exposure comes from drinking water  EPA
 calculates this level as follows:

             DWEL  =  RfD  (mg/kg/day) x body weight (kg)
                               water consumed (I/day*)

 *     The average daily water consumption is assumed to be two liters per dav
       (56 FR 3532).                                                     y

 For more information about these topics:            Refer to these questions:

 DWELs                                     IHA12.

 RfDs                                       III.A.8 - III.A.10.
 III.A.12.      What is the Relative Source Contribution?

      The Relative Source Contribution (RSC) is another component EPA uses to
 calculate an MCLG.  As discussed previously, the DWEL represents the protective
 level  of  exposure assuming  that 100  percent  of  a person's exposure  to  a
 contaminant comes from drinking water.  However, a person can be exposed to
 contaminants from various sources in addition to drinking water. The RSC is used
 to adjust the MCLG to account for the portion  of a person's daily exposure to a
 contaminant that comes from sources other than drinking water.

      Generally, EPA assumes that the RSC from drinking water is 20 percent of
the total exposure, unless other exposure data for the chemical are available.  The
 RSC may be as high as 80 percent (57 FR 31782).

For more information about these topics:            Refer to these questions:

DWELs                                    III.A.11.

MCLGs                                    II.2, II.4, and IH.A.1 - III.A.3.
                                                                      31

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                      Sources Cited in Section III.A.
Federal Register. Vol. 51, No. 185. Guidelines for Carcinogen Risk Assessment.
      September 24, 1986. [51 FR].
Federal  Register. Vol. 54, No.  97.  National Primary and Secondary Drinking
      Water Regulations; Proposed Rule. May 22, 1989.  [54 FR].
Federal Register. Vol. 56, No. 20. National Primary Drinking Water Regulations;
      Final Rule. January 30, 1991.  [56 FR].
Federal Register. Vol. 57, No. 138. National Primary Drinking Water Regulations;
      Synthetic Organic Chemicals and Inorganic Chemicals; Final Rule. July 17,
      1992.  [57 FR].
32

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  III.  Maximum Contaminant Level Goals (MCLGs) and Maximum
                      Contaminant Levels (MCLs)

                              III.B.  MCLs
 IM.B.1.
How does EPA set National Primary Drinking Water Regulations
(NPDWRs)?
       EPA sets  each  NPDWR, which  includes either  MCLs or TTs,  on a
 contaminant-by-contaminant basis.  For each contaminant to be regulated, EPA
 first sets an MCLG at a level that protects against health risks (see Section III.A.).
 EPA must then set each contaminant's MCL as close to its MCLG as is feasible,
 taking costs into consideration.  In some cases, when it is not feasible to set an
 MCL, EPA will develop a TT that establishes procedures  a PWS must follow to
 protect public  health,  taking into  account  data concerning  economics and
 technology.

       EPA may set a TT only if the Agency's Administrator determines that it is not
 economically or technologically feasible to ascertain the level of  a  regulated
 contaminant (SDWA, Section 1412(b)(7)(A)). However, even though a TT does not
 set a numerical limit for a contaminant, EPA identifies those TTs which would
 prevent known or anticipated adverse  health effects on  the public, including
 sensitive  members of  the  public,  to the  extent  feasible  (SDWA,  Section
 1412(b)(7)(A)).   In all  other cases, EPA sets an  MCL for  each  regulated
 contaminant.

      The SDWA states that EPA must set each MCL as close to its  MCLG as is
 feasible (SDWA, Section 1412(b)(4)).  The Act then defines feasibility as "feasible
 with the use of the best technology [BAT], treatment techniques and other means
 which the Administrator finds, after examination for efficacy under field conditions
 and not solely under  laboratory  conditions, are  available (taking  cost  into
 consideration)"  (SDWA,  Section  1412(b)(5».   Based on  the legislative  history
 associated with the Safe Drinking Water Act, EPA interprets this statutory language
 to mean setting numerical standards, or limits, at the smallest possible number that
 is feasible for large systems that have relatively clean source water (D/DBP Status
 Report, Overview Section, p 2).
For more information about these topics:

MCLs

NPDWRs

TTs
                             Refer to these questions:

                             11.1, II.3 -II.4, ll.6and 11.19.

                             III.B.2 - III.B.3 and Ili.B.6 - III.B.9.

                             11.1, and II.5-II.6.
                                                                     33

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III.B.2.      What  technological   concerns   are  factored   into   this
            determination?          ,

      EPA weighs several technological components when determining NPDWRs.
Each NPDWR lists technologies, treatment steps and other means that are feasible
for meeting the MCL  (57  FR 31797).  EPA evaluates all of these components
separately and together to  measure their influence on each MCL and/or TT.

      In deriving MCLs or TTs, EPA evaluates the availability and performance of
various technologies for removing the contaminant, the  ability of laboratories to
measure accurately and consistently the level of the contaminant with available
analytical methods and health risks associated with various contaminant levels to
ensure that the MCL will adequately protect public health (57 FR 31797-31798).

      In addition, EPA must take into account PWSs' ability to  comply with the
MCL  While the SDWA requires EPA to set MCLs and TTs as close to their
MCLGs as is feasible, EPA does not consider it technologically feasible  to set
MCLs so stringent that most systems could not possibly meet them.  "While the
legislative history indicates  that Congress intended that MCLs be set based upon
the better performing systems (i.e., large systems applying BAT to 'relatively clean
source water'), there is no indication that Congress envisioned establishment of
MCLs that would result in widespread noncompliance among water systems" (56
FR 26476).

For more information about these topics:            Refer to these questions:

BATs                                      IH-B-3 - IH-B.5.

MCLs                                     "-1. H-3 - IU- n-6 and IL19-

TTs                                       H-1 and "-5 - IL6-


III.B.3.       What are BATs, and how are they involved in setting MCLs?

       BAT stands for Best Available Technology, which is defined as any or all
technologies that after field and laboratory testing are judged to  be the most
effective technologies for achieving the MCL.  For synthetic organic compounds
(SOCs), the SDWA states that any BAT identified must be at least as effective as
granular activated carbon (GAG).  Formerly this term  was called  BTGA, Best
Technology Generally Available. However, the 1986 Amendments to the  SDWA
changed the name to BAT, and established a broader standard that allowed EPA
to choose a BAT that may not necessarily be in widespread use, as long as its
performance has been demonstrated in a reliable way (57 FR 31797).

       Although the SDWA states that a BAT's performance must be tested under
 broader conditions than laboratory conditions,  EPA does not believe that the Act
 requires field testing for each technology operating  on each contaminant as a
 prerequisite for specifying  a BAT for a specific contaminant  (56 FR  26498).
 34

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 Instead, EPA interprets the SDWA directive to permit a technology to be identified
 as a BAT for a contaminant where there has been successful field application
 of the technology for treatment of other compounds, coupled with laboratory or
 pilot-scale data on the contaminant to be regulated to verify that technology as
 BAT for the contaminant to be regulated.

       In some cases, EPA uses data on the capabilities of BATs as they  are
 projected for large systems with relatively clean source water, along with data on
 the capabilities of the analytical devices used to measure a contaminant in drinking
 water  when the Agency sets a numerical standard for a  contaminant  (57  FR
 31797).  BATs, then, are EPA's determination that available technology exists to
 remove or inactivate  each regulated contaminant to its MCL.  Indeed, a BAT
 indicates what amount of contaminant removal has been demonstrated through  the
 use of a particular technology.

       A BAT is not, however, a technology that must be used by a water system
 that exceeds an MCL.  BATs need  not be used by a system if the system can
 achieve the standard by using another approach. If, however, a system wants a
 variance (a waiver from having to comply with a regulation), it must first install  the
 BAT and demonstrate that its source water is of such poor quality that even BAT
 does not enable the system to comply with the MCL (SDWA, Section 1415).

 For more information about these topics:           Refer to these questions:

 BATs                                     II.B.2 and III.B.4 - III.B.5.

 MCLs                                     11.1. M.3 - II.4, II.6 and 11.19.


 III.B.4.      How are BATs chosen?

      The process of selecting a BAT incorporates several steps, ranging from
 conducting literature searches for information about various technologies to bench-
 scale or even field tests.  Since in some cases the selection of BATs may affect the
 numerical level of an MCL, the Agency considers various criteria when adopting
them for each regulated contaminant.

      EPA's initial step  is to identify all of the technologies that are capable of
 removing the contaminant from drinking water (57 FR 31797). Next, the Agency
examines each one, using a process to determine which one or ones are 'best'.
 In order to be chosen as  a BAT,  EPA generally requires that a treatment
technology meet certain conditions.  Specifically, EPA evaluates  whether the
technology:

      •     Is demonstrated at field scale or projected from pilot studies  or field
            data studies;

      •     Is compatible with other treatment technologies;
                                                                      35

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      •     Achieves effective contaminant removal;

      •     Is affordable to large drinking water utilities; and

      •     Performs as well as granular activated carbon filtration for synthetic
            organic compounds (SOCs).

      As discussed in the previous question, EPA does not consider field testing
to be essential for each specific contaminant.  "The technology, however, must
reasonably be expected to perform in a similar manner under field conditions
regardless of aberrations due to scale-up factors"  (57  FR 31809).

For more information about these topics:            Refer to these questions:

BATs                                       "-B.2, III.B.3 and III.B.5 - lil.B.6.


III.B.5.       Do Water systems have to install BATs?

      A PWS is not required to install the BATs in order to comply with the MCLs.
A PWS is required to install BAT if it wishes to apply for a variance under Section
1415 of the SDWA.

      According  to Framework for Decision-Making:  An EPA Perspective,
"Systems are  not required to use BAT in order to  comply with the MCL but can
use other technologies as long as they meet all drinking water standards and are
approved by  the State"   (Framework, p  2).  Indeed, application of a new
technology may be the last resort for systems, coming after alternative strategies
have been tried, such as mixing water from a variety of sources to dilute the
contaminant's presence in tap water or shutting down one source of contaminated
water in favor of using 'cleaner' sources.

      EPA's list  of BATs for  each regulated contaminant serves as a way for
systems to get a variance from meeting an MCL.  A variance, where allowed by
the State, permits a water system to continue supplying water  to its users for a
specified time period even though the water does not meet  a  drinking water
standard (SDWA  Pocket Guide, p. 7). To obtain a  variance, a system must apply
BAT first. Whenever a State issues a variance for a water system, the State must
set a schedule for the system's future compliance. In  some cases, the State will
also  set additional control measures, such as  requiring the system to provide
bottled water to its users (SDWA, Section 1415(a)(1)(A)(Mi)).  In some cases, the
BATs identified by EPA for  variances may  be different from those  listed for
determination of the MCL.

For more information about these topics:            Refer to these questions:

BATs                                      "I-B.2 - III.B.4 and III.B.6.

Variances/Exemptions                         IV.8 -1V. 11.
 36

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 III.B.6.      What cost concerns are factored into the MCL determination?

       The SDWA directs EPA to take costs into consideration when setting MCLs.
 EPA considers the costs of installing, operating and maintaining the BAT in order
 to treat the water.

       EPA considers the water treatment costs to PWSs when it sets MCL levels.
 In calculating these treatment costs, the Agency does not assume that every PWS
 will use the BATs. Some systems will hot need to treat their water because they
 are at or below an MCL for a particular contaminant. Others may use alternatives
 other than BAT to treat their water effectively. In estimating costs, EPA considers
 varying source water quality, the potential difficulty a PWS may experience when
 operating and maintaining a BAT and the impact of using a BAT on other drinking
 water  regulations, i.e., whether installing a BAT to remedy one contaminant may
 adversely affect the level of other compounds (Chafee Report, p.40).

 For more information about these topics:            Refer to these questions:

 BATs                                       III.B.2 - III.B.5.

 c°sts                                      HI.B.7.

 III.B.7.      Does EPA factor in nationwide costs when setting NPDWRs?

       The SDWA does not  require  EPA to calculate the nationwide  costs
 associated with each regulation when setting an MCL.  However,  EPA  does
 perform this analysis for many of its rules in the context of a Regulatory Impact
 Analysis (RIA).

       For 'major' rules, those that are expected to generate significant costs, EPA
 must perform an RIA, a formal analysis that weighs the estimated economic  costs
 against the perceived public health benefits of a regulation. When performing an
 economic analysis for an RIA, EPA must consider a variety of information, including

       •     Occurrence data, to determine the number of PWSs violating MCLs;

       •     Treatment  and  waste  disposal  cost  data and  corresponding
            probabilities that PWSs will select each of the various treatment and
            disposal options,  to estimate the system  level and aggregate costs
            of achieving the proposed MCLs; and

       •    ' Monitoring costs, to estimate  aggregate costs  of the monitoring
            requirements (57  FR 31831).

      All of these costs are factored into RIAs although they do not directly affect
the derivation of an MCL.

For more information about these topics:           Refer to these questions:
Costs                                      Ili.B.e.
                                                                      37

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III.B.8.      Are health risks also factored into the determination of MCLs?
      Yes, health risks dictate the MCLG, and the law requires EPA to set the
MCL as close to the MCLG as is technologically and economically feasible.

      For carcinogens, EPA's goal is to ensure that the maximum risk at the MCL
falls within the annualized 10"4 to 10/6 risk range, which the Agency considers to
be protective of human health. This risk range estimates the excess individual risk
from a carcinogen over a person's lifetime (57 FR 31797-31798). Pathogens and
coliforms regulated to date also have MCLGs of zero because even one protozoan
pathogen or virus pathogen may cause an infection in some people; MCLs  (or TT
requirements) are set to be protective of these health risks.
For more information about these topics:

Cancer Risk Range

MCLGs

MCLs
Refer to these questions:

III.A.6.

II.2, II.4 and III.A.1 - III.A.3.

II.3-II.4, II.6, III.B.1, III.B.3, III.B.6
III.B.8 and III.B.10.
III.B.9.       What are analytical  methods, and how are they involved with
             MCLs?

      Analytical methods are test methods that must be approved by EPA for
measuring the presence and concentration of pollutants (Index to Test Methods,
p.i). When EPA sets an MCL for a contaminant, it lists the approved method(s)
that laboratories must use to measure the contaminant in drinking water.

      Since approved analytical methods must be used to measure the level of
contaminants, the laboratory's ability to use the approved methods to measure
with precision  and reliability is  important to  determine  whether a  PWS is in
compliance with the MCLs.  In most cases, the laboratory will have the ability to
measure a contaminant well below its MCL For contaminants that have an MCLG
of zero, the precision of the  analytical method and the treatment abilities of the
BAT may be  more significant since EPA must set an MCL as close to an MCLG
as is feasible, and it would not be technologically feasible to set an MCL of zero.

      EPA selects each analytical method carefully using a variety of criteria, both
technical and economical.  EPA evaluates methods "based on the following factors:
(1) reliability (i.e., precision/accuracy) of the analytical results; (2) specificity in the
presence of interferences;  (3)  availability of enough equipment and trained
personnel to implement a national monitoring program (i.e., laboratory availability);
(4) rapidity of analysis to permit routine  use;  and (5) cost of analysis to water
supply systems"  (57 FR 31798). Evaluation of the above criteria enables EPA to
select analytical methods that are feasible for laboratories across the nation.
For more information about these topics:
Analytical Methods
Refer to these questions:
III.B.10 - III.B.13.
38

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111.B.10.     What is an MDL?

      MDL stands for Method Detection Level, the minimuim concentration of a
chemical that can be measured and reported with 99-percent confidence that the
true value is greater than zero  (56 FR 26510).

      "The MDL is a result of measurements made by an experienced laboratory
under controlled research-type conditions" (56 FR 26510).  An analyst derives
these levels to serve as an indicator of the minimum concentration of a chemical
that a laboratory can detect in a single sample, and MDLs may be used to evaluate
the significance of a single measurement in future samples (40 CFR 136, Appendix
B).  MDLs  may also be used to derive the Practical Quantitation Level (PQL) for
a chemical. A PQL is the level that can  be routinely monitored by laboratories
under normal operating conditions. When deriving PQLs,  EEPA uses MDLs only
when laboratory data, such as performance evaluation studies, are not available.

For more information about these topics:            Refer to these questions:

MDLs                                      III.B.11 and III.B.13.

PQLs                                       III.B.12 - lli.B.14.
ill.B.11.     How is an MDL derived?

      EPA derives MDL levels in a laboratory, using a method detailed in Part 136,
Appendix B of the Code of Federal Regulations (40 CFR 136, Appendix B).

      According  to 40 CFR 136, Appendix B, the first procedure  involves
estimating the lowest detection limit.  Then this estimate is; tested by having a
laboratory prepare two types of water samples:  one that is as free as possible of
the compound for which the MDL is being derived (called a blank) and another
that contains this compound at a concentration as close to the estimated MDL as
possible  (called analyte spiked into  reagent water).   Seven  specimens are
generated from the analyte  spiked into  reagent water and  processed.  If the
specimen results are in the correct range for determining the MDL, the laboratory
would calculate the variance and standard deviation of the measurements.  Then,
the MDL  is computed using a formula specified in 40 CFR 136, Appendix B.

For more information about these topics:            Refer to these questions:

MDLs                                      MI.B.10 and III.B.13.
                                                                       39

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III.B.12.      What is a PQL?

      PQL stands for Practical Quantitation Level; this term is defined as a level
that can be measured by good laboratories under normal operating conditions with
specified limits of precision and accuracy (57 FR 31797).

      These levels should be routinely attained by certified laboratories within a
specified acceptance range, but laboratories are not required to do this in'order
to be certified.  Using data from EPA and State laboratories, the Agency sets
acceptance limits for required accuracy and precision  on a contaminant-by-
contaminant  basis.  For each regulated contaminant,  EPA tries to establish the
lowest PQL with the tightest acceptance levels consistent with available health
effects information.

For more information about these topics:            Refer to these questions:

PQLs                                        IH.B.13 - III.B.14.
IH.B.13. How is a PQL derived?

       In general, EPA can derive a PQL, or Practical Quantitation Level, in either
of two ways. The Agency may determine this level through performance evaluation
(PE) studies or it may estimate the PQL from the MDL if adequate data are not
available from the PE studies  (56 FR 26511).

       EPA can estimate a PQL for a contaminant by multiplying the MDL by 5 to
10. Five is used when the ten times multiplier would cause the MCL to be higher
than1 the MCLG or greater than a 10"4 lifetime cancer risk.  "In cases where PE
studies are unavailable or inadequate, EPA believes that a PQL set  at '5 to  10
times' the  MDL achieved  by good laboratories is  generally a fair expectation for
routine operation  of most qualified State and commercial laboratories" (56 FR
26511).  This estimation  is generally done, though, only if there  is insufficient
information from laboratory studies, particularly PE studies. If data from PE studies
are available,  EPA generally sets PQLs at a concentration where at least 75% of
the laboratories involved in the PE studies are able to measure within a specified
acceptance limit of the contaminant's true value  (56 FR 26511).

For more information about these topics:            Refer to these questions:

MDLs                                        III.B.10-III.B.11 and III.B.13-III.B.14.

PQLs                                        lfl.B.12 and III.B.14.
 40

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III.B.14.      How do the MDL and PQL differ?

      These terms differ in definition, measurement practices and by use, and they
should not be used interchangeably. MDLs may have been met once by an EPA
or State laboratory, but PQLs should be routinely met by all certified laboratories.

      While these levels of measurement are both used in the context of analytical
methodology, they differ from each other in various respects.  First,  these levels
refer to different types of measurement practices.  Unlike PQLs, MDLs derived by
EPA are not designed to be met by routine laboratory analysis-they may not be
necessarily reproducible over time in a given laboratory (56 FR 26510).  PQLs, on
the other hand, are levels that certified laboratories should routinely measure with
a specified degree of reliability and precision.

      PQLs and MDLs are used differently by EPA. PQLs may be used in some
cases as  one of  the factors examined by EPA when deriving  MCLs.   MDLs,
conversely, are used for (1) deriving PQLs if no PE study data exist and/or (2) as
an indicator of the minimum concentration of a chemical that a laboratory can
detect in a single sample, which  may be used  to evaluate the significance of a
single measurement in future samples.  Under current regulations, MDLs are also
used to trigger additional monitoring  for SOCs.   As such,  MDLs,  which are
generally 5 to 10 times lower than PQLs, are not used directly in the derivation of
MCLs or as a standard that a certified laboratory should  meet.

For more information  about these topics:           Refer to these questions:

MDLs                                      III.B.10 -III.B.11.

                                          IH.B.12 - III.B.13.
                                                                      41

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                     Sources Cited in Section III.B.
Code of Federal Regulations, Title 40 CFR 136, Appendix B. Definition  and
      Procedure for the Determination of the Method Detection Limit. Government
      Printing Office. July 1993. [40 CFR 136, Appendix B].

Federal Register. Vol. 56, No. 20. National Primary Drinking Water Regulations;
      Final Rule. January 30, 1991. [56 FR].

Federal Register. Vol. 56, No. 110. Maximum Contaminant  Level Goals  and
      National Primary Drinking Water Regulations for Lead and Copper; Final
      Rule. June?, 1991. [56 FR].

Federal Register. Vol. 57, No. 138. National Primary Drinking Water Regulations;
      Synthetic Organic Chemicals and Inorganic Chemicals; Final Rule. July 17,
      1992. [57 FR].

Nelson, Margaret. Index to EPA Test Methods. EPA Region I (EPA/901/3-88/001).
       1988. [Index to Test Methods].

Regli,  Stig,  et al. Framework  for  Decision  Making: An  EPA  Perspective
       (EPA/811/R-92/005). EPA Office of Water. August 1992. [Framework].

U.S. Congress.  Safe  Drinking  Water  Act. 42 U.S.C. Section 300f et seq. June
       1986. [SDWA].

U.S. Environmental Protection Agency.  Evaluation of Demonstration Technologies: -
       Quail Creek Water Supply System (EPA/812/R-93/001). October 1992.
       [Quail Creek Demonstration Project].

U.S. Environmental Protection Agency.  Technical and Economic Capacity of States
       and Public  Water Systems  to  Implement Drinking Water  Regulations:
       Report to Congress (EPA 810/R-93-001). September  1993.   [Chafee
       Report].

U.S. Environmental Protection Agency. The Safe Drinking Water Act:   A Pocket
       Guide to the Requirements for the Operators of Small Water Systems  (EPA
       570/9-90-600). September 1990.   [SDWA Pocket Guide].

U.S.  Environmental  Protection  Agency.  Status Report  on  Development of
       Regulations for  Disinfectants  and Disinfection  By-Products   (No  EPA
       Number). EPA Office of Groundwater and Drinking Water. June 1991.
       [D/DBP Status Report, Overview Section].
 42

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              IV. Requirements Established by NPDWRs
                 Other Than MCLGs and MCLs/TTs
IV.1.   What other requirements are established by NPDWRs?

       EPA establishes other requirements concerning drinking water contaminants
in addition  to setting MCLGs and  either  MCLs or TTs.  For each regulated
contaminant, EPA  establishes monitoring, reporting,  recordkeeping and public
notification requirements as well as specifying the approved analytical methods and
BATs. Along with NPDWRs, EPA sets requirements States must meet in order to
obtain and retain primacy.

       MCLGs and MCL/TTs are  not the only requirements established by EPA for
each  regulated contaminant.   EPA regulations establish requirements on when,
where and  how often  PWSs must monitor their water for each  regulated
contaminant as well as what data to report and  to whom they have to report it.
The Agency also specifies recordkeeping  and public notification requirements,
approved analytical methodology and BATs for each regulated contaminant.

For more information about these topics:            Refer to these questions:

Analytical Methods                             III.B.6 and III.B.10.

BATs                                       III.B.2 - III.B.6.

MCLGs                                     11.2, 11.4 and III.A.1 - IH.A.3.

MCLs                                       II.3 - II.4, II.6, III.B.1, III.B.3, III.B.6 -
                                           III.B.7 and III.B.9 -III.B.10.

Monitoring                                   IV.2 - IV.6.

NPDWRs                                    II.8-11.12 and 11.17.

Public  Notification                             IV.11-IV.13.

Recordkeeping                               IV.8 - IV. 10.

Reporting                                    IV.7.

TTs                                        11.1, and II.5-II.6.
                                                                       43

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IV.2.  How frequently do Public Water Systems (PWSs) have to monitor for
      regulated contaminants?

      There is no universal monitoring schedule that applies to all NPDWRs. EPA
requires PWSs to monitor for some contaminants monthly (up to 480 times a
month for conforms, depending on a PWS's size, etc.), some quarterly and others
annually, triennially and  even once every nine years.   EPA  sets a monitoring
schedule for each contaminant on a case-by-case basis.   The Agency has,
however, developed a nine-year framework, called the Standardized Monitoring
Framework (SMF), that attempts to simplify/unify monitoring for many chemicals,
although not all chemicals nor other contaminants such as microorganisms will be
monitored under the SMF.   For a more detailed  description of the monitoring
requirements under the  SMF,  see the Consolidated  Rule  Summary for the
Chemical Phases, a document that is available from EPA's Safe Drinking Water
Hotline (1-800-426-4791).

      When  developing monitoring  requirements, the  Agency  treats  each
contaminant individually, considering factors such as each one's health effects,
seasonality of occurrence in water, volatility, etc.  For  most contaminants, EPA
specifies criteria that could trigger systems into reduced or increased monitoring
for particular contaminants.  Monitoring varies by system size, by source(s) of
water supply and by contaminant.  Monitoring for contaminants with acute health
effects (such as conforms) is also more frequent.

For more information about these topics:           Refer to these questions:

Monitoring                                  IV.1  - IV.6.
IV.3.  Where must Public Water Systems (PWSs) monitor for contaminants?

      It depends on the contaminant for which the systems are monitoring.  For
each  regulated compound,  EPA specifies where systems must monitor and any
conditions that could lead to variations in monitoring sites.

      Just as EPA establishes monitoring schedules for each contaminant on a
contaminant-by-contaminant basis, the location or locations systems must monitor
also may vary by contaminant. In most cases, PWSs will take samples at the entry
point(s) to their distribution  systems. However, in some cases, such as for lead
and copper, systems will have to take tap water samples. In other cases, such as
measuring turbidity under the Surface Water Treatment Rule, a system  may have
to take  a  sample at a location before the water is disinfected.  Another example
from the Surface Water Treatment Rule is the requirement that unfiltered systems
monitor their source water.

For more information about these topics:            Refer to these questions:

Monitoring                                  IV.1 - IV.2 and IV.4 - IV.6.
 44

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 IV.4.  Does the source of water (i.e., surface water or ground water or a
       mixture of the two) affect the way systems monitor?

       In  some cases,  the  source  of water that a PWS  uses  may  affect its
 monitoring requirements.

       Depending on the contaminant under regulation, monitoring requirements
 such as sampling frequency, number of samples, locations of sampling sites or
 even whether the PWS has to monitor for that contaminant at all may be affected
 by a system's type of source water. Some contaminants, such as Giardia lamblia,
 are  associated with surface water.  Therefore, the Agency requires only PWSs
 using surface water sources or ground water under the direct influence of surface
 water to treat their water to inactivate Giardia lamblia.  Other contaminants may
 have different sampling frequencies depending on whether a water system uses
 surface water  or ground water.  As  stated above,  when  EPA  regulates a
 contaminant, the Agency will specify variations in monitoring for ground water and
 for surface water, if any apply.

 For more information about these topics:           Refer to these questions:

 Monitoring                                  IV.1 . iv.3 and JV.5 - IV.6.
 IV.5.  What other factors can affect monitoring?

      There are several factors that can affect monitoring for a contaminant other
 than a PWS's source water or contaminant-specific considerations. These factors
 include type and size  of a PWS, past monitoring history for a compound and a
 State's discretionary power.

      The Agency sets monitoring  requirements for each contaminant  on an
 individual basis.  When EPA establishes these requirements, the Agency evaluates
 a  variety  of  factors in addition  to characteristics  of  the contaminant  under
 regulation. One such  factor is the type of PWS that will be required to conduct
 monitoring. CWSs, NTNC water systems and TNC water systems serve different
 populations.  In general, TNCs monitor for fewer contaminants (those with acute
 health effects) compared to CWSs and NTNCs.

      Another factor influencing  monitoring is the size of a PWS.  For some
 regulations, such as the Lead and Copper Rule, EPA requires larger systems to
 begin monitoring for a contaminant before smaller ones.  Under  the SMF, all
systems must monitor  within a three-year period  regardless of size, but many
States require larger systems to monitor first.  For some contaminants, EPA
requires only systems that are of a certain size to monitor or larger systems to take
more samples than smaller ones.  This is the case with the Total Trihalornethanes
Rule, which (among other things) requires only PWSs serving more  than 10,000
persons to monitor for these contaminants. For coliforms, the more people a PWS
serves, the more samples it must  collect.
                                                                     45

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      A State sometimes uses a PWS's past history as a condition for reduced
monitoring.   For instance, under the SMF, if a system does not detect the
presence of a chemical, they may go to reduced monitoring.  Conversely, if the
system violates an MCL or detects a contaminant at a prescribed detection limit,
the PWS must increase its monitoring for that contaminant. A State may also set
monitoring requirements for certain compounds, as long as the requirements are
at least as stringent as EPA's.
For more information about these topics:

Monitoring

PWSs
Refer to these questions:

IV.1 - IV.4 and IV.6.

I.2 -1.9.
1V.6.  What is "unregulated" contaminant monitoring?

      Unregulated contaminants are chemicals for which EPA has set enforceable
monitoring requirements but which do not have MCLGs, MCLs or TTs  (56 FR
3569). EPA uses the data collected by this monitoring to determine whether these
contaminants should be regulated in the future.

      Since these contaminants do not have a regulatory MCL or TT, the Agency
considers them to be unregulated contaminants even though EPA requires water
systems to monitor for them. This requirement is called unregulated contaminant
monitoring.  Like monitoring requirements for  regulated contaminants, EPA  may
vary unregulated contaminant monitoring requirements according to system size
and type as well as at the State's discretion.  The SDWA requires PWSs to provide
the results of any unregulated contaminants  to their users upon their request
(SDWA, Section 1445(a)(5)).
For more information about these topics:

MCLs


Monitoring

PWSs

TTs
Refer to these questions:

11.1, II.3 - II.4, II.6, III.B.1, III.B.3, III.B.6
III.B.7 and III.B.9 - III.B.10.

IV.1 - IV.5.

I.2 -1.9.

11.1 and II.5 -11.6.
 IV.7.  What are the reporting requirements to the State and/or EPA?

       A PWS must report several types of information to the State and/or to EPA.
 There are bpth general reporting requirements in 40  CFR 141.31 and  specific
 reporting requirements contained with each regulation.
 46

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       Under 40 CFR 141.31, PWSs must report the results from all tests or
 analyses required by the regulations.  These are to be reported within the first 10
 days following the month  in which the results were received or within 10 days
 following the end of the monitoring period, whichever is shorter.  This time period
 applies unless the supplier of water fails'to comply with any NPDWR in which case
 reporting is required within  48 hours.   PWSs are also required to  report the
 following under 40 CFR 141.31: (1) a representative copy of any public notification
 material sent to customers or to the media within 10 days of completion of public
 notice and (2) any copies of any records requested by the State (40 CFR 141.31).
 In addition, certain regulations (e.g., the Lead and Copper Rule and the Surface
 Water Treatment  Rule) require PWSs to report  other  information.  These
 requirements are specified in the rules.

 For more information about these topics:           Refer to these questions:

 Monitoring                                  IV.2 - IV.6.

 Public Notification                             IV.11-IV.13.

 Recordkeeping                               IV.8 - IV.10.

 Reporting                                   IV.1.

 IV.8.  What records do Public Water Systems (PWSs) have to maintain?

       Again, there are both general recordkeeping requirements and regulation-
 specific  requirements.  Generally, PWSs have to  maintain monitoring results,
 accounts of actions  taken by the  system to correct any violations, reports
 concerning sanitary surveys and records concerning any variances or exemptions
 that the State has granted  (40 CFR 141.33).

       EPA requires all PWSs to maintain these types of records at or near their
 premises.  For monitoring  results, EPA also requires that these records include
 certain information such as (1) the date, place and time of sampling as well as the
 name of the person doing the sampling; (2) explanation of the type of sampling,
 e.g., whether the sample is a distribution sample, check sample, raw or processed
 water sample, etc.; (3) date of the laboratory analyses of samples; (4) the name
 of the laboratory and the person who performed the analyses;; (5) the test method
 used and (6) the sampling results (40 CFR 141.33(a)(1)-(6J).   In addition,  EPA
 requires  PWSs to keep additional records for certain regulations, especially the
 Lead and Copper Rule and the Surface Water Treatment Rule. See 40 CFR 141.91
for Lead  and Copper Rule requirements and 40 CFR 141.75 for the Surface Water
Treatment Rule requirements.

 For more information about these topics:            Refer to these questions:

Analytical Methods                             III.B.6 and III.B.K).

Monitoring                                   IV.2 - IV.6.

Recordkeeping                                IV.? and IV.9 - IV.HO.

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IV.9.  Are these records available to the public?

      The SDWA does not require PWSs to make all monitoring records available
to the public, although the public may request this information of PWSs, and PWSs
may chose to provide it. Section 1445(a)(5) of the SDWA requires PWSs to notify
the persons served by the system of the availability of the results of its monitoring
program for unregulated contaminants only. The  SDWA does not require PWSs
to make available to the public the monitoring results for regulated contaminants.

      PWSs are required to notify consumers when they have violated an NPDWR
or the  requirements of  any schedule prescribed  pursuant  to  a  variance  or
exemption [40 CFR 141.32]. The primary purpose of public notification is to inform
consumers of any potential adverse health effects related to the drinking water
being supplied to them, and to identify the steps consumers can take to minimize
the health impact.

For more information about these topics:      Refer to these questions:

Public notification                       IV.11-IV.13.

IV.10. How long must PWSs keep their records?

      The time period that a PWS is required to keep its records varies depending
on the type of record. For each type of record that a PWS is required to maintain,
EPA establishes a time period that the record must be kept.

      For bacteriological sampling results, the records must be kept for at least
5 years, and chemical sampling  results must be kept for at least 10 years. For the
Lead and Copper  Rule, records must be maintained for 10 years, as well.  PWSs
must retain records that detail any actions taken to correct violations for at least
3 years after the last action was taken, while they must keep records concerning
sanitary surveys for at least  10 years.  PWSs must retain  records of variances
and/or exemptions for at least 5 years (40 CFR 141.33 (a)-(d)).

For more information  about these topics:            Refer to  these questions:

Recordkeeping                               IV.7 - IV.8.

IV.11. What is public  notification, and when do PWSs have to do it?

       Public notification  is the process used by a PWS to inform its users that
the system has violated a drinking water regulation. The notice  must be clear,
understandable, not unduly technical, multilingual if appropriate and include the
name and telephone number of the operator or contact person for additional
information.  Each time a PWS  fails to comply with a regulation,  it must
announce the violation, warn of potential adverse health effects using the
mandatory language in EPA's regulations, describe the steps it is taking to
remedy the problem and, in some cases, direct users to alternative sources of
drinking water.  The timing of this notification varies, depending  on the type of


48

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 violation that has occurred.  Also, the type of notification may vary based on the
 type of PWS which must provide it.

       There are two categories of violations that require public notification: Tier
 1 and Tier 2.  Each tier has  its own notification schedule. Tier 1 includes MCL,
 TT and variance/exemption  violations. If the violation is a Tier 1 violation, then
 the PWS will have to publish notification in a newspaper as  soon as possible
 but no later than  14 days after the violation and provide written notification on or
 with the water bills within 45 days of the violation. For acute Tier 1 violations,
 that is, violations  of the MCLs that may pose an acute risk to public health (e.g.,
 violations for nitrate, nitrite, fecal conforms or E. coli, waterborne disease
 outbreaks and any other compound deemed to be acute by the State), PWSs
 must notify area radio and television stations as soon  as possible but no later
 than 72 hours after the violation  occurs.  Notice of Tier 1 violations must be
 repeated at  least  once every 3 months for as long as the violation exists.

       For Tier 2 violations, however, systems must publish  notification in a local
 newspaper within 3 months of the violation. Tier 2 violations include failure to
 comply with monitoring requirements and announcement that the State has
 granted a variance or exemption from complying with a regulation to the PWS.
 As with Tier 1 violations, PWSs must repeat this notification  every three months
 for as long as the system is  experiencing a Tier 2 violation.

       If the  PWS is a Non-Community System, it may give notice by hand
 delivery or by continuous posting in conspicuous places within the area served
 by the system.  Hand delivery notice must be delivered as soon as possible but
 no later than 72 hours for acute violations and no later than 14 days after the
 violation occurs for non-acute violations.  It must be repeated every 3 months
 for as long as the violation exists. Posting must be continuous for as long  as
 the violation  exists.
For more information about these topics:

MCLs


Public Notification

TTs
Refer to these questions:

11.1, II.3 - II.4, II.6, III.B.1, III.B.3, III.B.6
III.B.Tand III.B.9 - III.B.10.

IV. 12 - IV. 13.

11.1 and II.5 - II.6.
IV.12. What is mandatory health effects language, and when would systems
      use it for public notification?

      Mandatory health effects language provides information on the potential
adverse health effects of contaminants.  It is the language, specified by EPA, that
PWSs must copy word-for-word when notifying the public of violating an MCL or
TT  requirement for a contaminant.  Public notice  may also include additional
information.
                                                                        49

-------
      A  PWS  must include mandatory health  effects  language in its public
notification whenever the system violates an MCL, TT,  exemption or variance
schedule, or even when a water system is granted an exemption or variance for
a contaminant, unless EPA has not specified language for a particular contaminant
(40 CFR 141.32(e)). In that case, a PWS would still have to inform its users of
potential adverse health effects in such a way that the  language used in the
notification can be clearly understood by its users, without using highly technical
language, small print or any other device likely to frustrate the  reader (40 CFR
141.32(d)).
For more information about these topics:

Mandatory Health Effects Language

Public Notification
Refer to these questions:

IV. 13.

IV.11 andlV.13.
IV.13. Do  all  regulated  contaminants  have  mandatory  health  effects
      language?

      No.  Currently only 76 out of the 84 regulated contaminants have mandatory
health effects language.

      EPA has developed mandatory health  effects language for most drinking
water contaminants.  However,  the  Agency  has not yet developed mandatory
language for some contaminants, including arsenic, the radionuclides, endrin and
total trihalomethanes. When  EPA promulgates regulations (either MCLs or TTs)
for these contaminants, the Agency may also specify the mandatory health .effects
language to be used in public notification.
For more information about these topics:

Mandatory Health Effects Language

Public Notification
Refer to these questions:

IV.12.

IV.11 -IV.12.
50

-------
                       Sources Cited in Section IV

Code of Federal Regulations, Title 40 CFR 141. Government Printing Office. July
      1993. [40 CFR 141].
Federal Register. Vol. 56, No. 20. National Primary Drinking Water Regulations;
      Final Rule. January 30, 1991. [56 FR].
U.S. Congress. Safe Drinking Water Act. 42 U.S.C. Section 300f et seq. June 1986
      [SDWA, Section].
                                                                     51

-------

-------
               APPENDIX A:





TABLE 1: Applicability/Coverage by Contaminant







   TABLE 2:  Applicability/Coverage by Rule

-------

-------
                    APPENDIX A
  Table 1: Applicability/Coverage by Contaminant
i /:c^imiait^rr:
Acrylamide
Alachlor (Lasso)
Aldicarb*
Aldicarb sulfoxide*
Aldicarb sulfone*
Antimony
Arsenic
Asbestos
Atrazine
Barium
Benzene
|Benzo[a]pyrene
Beryllium
Beta particles & photon
emitters
Cadmium
Carbofuran
Carbon tetrachloride
Chlordane
Chromium
Copper
Cyanide
2,4-D (Formula 40,
Weeder 64)
Oalapon
Di(2-ethylhexyl)adipate
Di(2-ethylhexyl)
phthalate
i , «E$$Y
ii
ii
lib
lib
lib
V
Interim
II
II
lib
I
V
V
Interim
II
II
I
II
II
LC
V
II
V
V
V
TYRI^
soc
soc
soc
soc
soc
IOC
IOC
IOC
soc
IOC
voc
soc
IOC
Had
IOC
SOC
voc
soc
IOC
IOC
IOC
soc
soc
soc
soc
^ smiM*
CWS.NTNC.TNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS
CWS.NTNC :
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
•»••-•
Ail sizes
All sizes
,AII sizes
i.
All sizes
All sizes
All sizes
All Sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
• > 100,000 persons
• using surface water
• deemed to be vulnerable
by the state
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
Indicates the regulation is not currently in effect.

-------
CONTAMINANT;
Dlbromochloropropane
o-Dlchlorobenzene
p-DIchlorobenzene
1,2-DIchloroethane
1,1-DIehloroethylene
cls-1,2-
Dlchloroethylene
trans-1,2-
Dlchloroethylene
Dlchloromethane
1 ,2-DichIoropropane
DInoseb
Diquat
Endothall
Endrin
Epichlorohydrin
Ethylbenzene
Ethylene dibromide
Fluoride
Glardla lamblia
Glyphosate
Gross alpha particle
activity
Heptachior
Heptachlor epoxide
Heterotrophic plate
count
Hexachlorobenzene
Hexachiorocyclo-
pentadiene
Lead
^<" s>, ••„;• J!* *• "
II
II
I
I
I
II
II
V
II
V
V
V
V
II
II
II
FL
SWTR
V
Interim
II
II
SWTR
V
V
LC
-, »TY£₯CJ
soc
voc
voc
voc
voc
voc
voc
voc
voc
soc
soc
soc
soc
soc
voc
soc
IOC
Bact
soc
Rad
SOC
SOC
Bact
SOC
SOC
IOC
'swtBMi *^'i
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC.TNC
CWS.NTNC
CWS.NTNC
CWS
CWS.NTNC.TNC
CWS.NTNC
CWS
CWS.NTNC
CWS.NTNC
CWS.NTNC.TNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
SIZE - , ,-,- -, /

All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes

-------
! \^omm&t^r *
Legionella
Lindane
Methoxychlor
Mercury
Monochlorobenzene
Nickel
Nitrate (as nitrogen)
Nitrite (as nitrogen)
Total Nitrate/Nitrite
Oxamyl (Vydate)
Pentachlorophenol
Picloram
Polychlorinated
biphenyls (PCBs)
Radium 226 &
Radium 228 combined
Selenium
Simazine
Styrene
2,3.7,8-TCDD (Dioxin)
Tetrachloroethyiene
Thallium
Toluene
Total Coliforms
(including fecal
cdiforms & £ coll
Total Trihalomethanes
Toxaphene
2,4,5-TP (Silvex)
\ *&&*&;
SWTR
II
II
II
11
V
II
II
II
V
lib
V
II
Interim
II
V
II
V
II
V
II
TC
Interim
II
II
'•.'.. A^ vW> .. *
^IVWE-
Bact
SOC
SOC
IOC
VOC
IOC
IOC
IOC
IOC
SOC
SOC
SOC
SOC
Rad
IOC
SOC
VOC
SOC
VOC
IOC
VOC
Baet
DBP
SOC
SOC
: - ' *i_ ' •*.' **"••'' '•• "•••-' '
u^fimamsa- '
CWS.NTNC.TNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC.TNC
CWS.NTNC.TNC
CWS.NTNC.TNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC |
CWS.NTNC
CWS.NTNC
CWS.NTNC.TNC
cws
CWS.NTNC
CWS.NTNC
:' % % - * ' ""' ' ^ , ' '
SIZE ..';-'"":,
All sizes
All sizes
All sizes
All sizes
All sizes
i
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
AH sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
• > 10,000 persons
• Add a disinfectant ,
(oxidant)
All sizes
All sizes

-------
CONTAMINAtfT o
1 ,2,4-TrichIorobenzene
1 ,1 ,1 -Trichloroethane
1 ,1 ,2-Trichloroethane
Trichloroethylene
Turbidity
Vinyl chloride
Viruses
Xylenes
*W&?-
V
I
V
I
SWTR
I
SWTR
II
£ ^ •*%•£" x^jf^v#" •
voc
voc
voc
voc
Ind
VOC
Micro
VOC
$$&&'• J:
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC.TNC
CWS.NTNC
CWS.NTNC.TNC
CWS.NTNC
" SHE ' '
All sizes
All sizes
All sizes
All sizes
All Sizes
All sizes
All sizes
All sizes
1)     I means Phase I Final Rule (52 FR 25690. dated July 8.1987).
       II means Phase II Final Rule (56 FR 3526. dated January 30, 1991).
       lib means Phase lib Final Rule (57 FR 30266. dated July 1,1991).
       V means Phase V Final Rule (57 FR 31776. dated July 17, 1992).
       FL means Rouride Final  Rule (51 FR 11396, dated April 2, 1986).
       LC means Lead and Copper Final Rule (56 FR 26460, dated June 7, 1991).
       Interim means National Interim Primary Drinking Water Regulations (dated before 1986).
       SWTR means Surface Water Treatment Final Rule (54 FR 27486, dated June 29, 1989).
       TC means Total Coiiform Final Rule (54 FR 27544, dated June 29, 1989).

2)     Bact means bacteria.
       DBF means Disinfection  Byproduct.
       Ind means indicator.
       IOC means Inorganic Contaminant.
       Micro means microbiological contaminant.
       Rad means radionuclide.
       SOC means Synthetic Organic Contaminant.
       VOC means Volatile Organic Contaminant.

3)     CWS means Community Water System.
       NTNC means Non-Transient, Non-Community water system.
       TNC means Transient, Non-Community water system.

-------
            APPENDIX A




Table 2: Applicability/Coverage by Rule
CONTAMINANT
Arsenic Rule3
Fluoride Rule
TYPE1
ioc
IOC
SYSTEM2
cws
cws
SIZE
Alt sizes
f Alt sizes
Lead and Copper Rule
Copper
Lead
IOC
IOC
CWS.NTNC
CWS.NTNC
All sizes
All sizes
Phase 1 Rule (VQCs)
Benzene
Carbon tetrachloride
p-Dichlorobenzene
1 ,2-Dichloroethane
1 , 1 -Dichloroethylene
1,1,1 -Trichloroethane
TrichloroethyJene
Vinyl Chloride
voc
voc
voc
voc
voc
voc
voc
voc
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
Phase II Rule
Acrylamide
Alachlor
I Asbestos (fiber >10 microns)
Atrazine
Carbofuran
Cadmium
Chlordane
Chromium (total)
Dibromochloropropane (DBCP)
o-Dichlorobenzene
cis-1 ,2-Dichloroethylene
soc
soc
IOC
soc
soc
IOC
soc
IOC
soc
voc
voc
CWS.NTNC.TNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes

-------
f— 	 1
CONTAMINANT
===== 	 '• 	 ' 	 '
trans-1.2-
Dichloroethylene
1 ,2-Dichloropropane
2,4-D
I Ethylbenzene
Ethylene dibromide
(EDB)
j Eplchlorohydrin
I Heptachlor
	 : 	 	 	
) Heptachlor epoxide
LJndane
	 : 	
I Mercury
j Methoxychlor
Monochlorobenzene
	 — 	
I Nitrate
P Nitrite
Polychiorinated biphenyis
(PCB)
Selenium
	 	 	
|] Styrene
Tetrachloroethylene
	 — 	
|| Toluene
Total Nitrate/Nitrite
[j
|| Toxaphene
I 2,4,5-TP (Silvex)
| Xylenes (total)
TYPE
:
voc
voc
soc
voc
soc
soc
soc
soc
soc
IOC
soc
voc
IOC
IOC
soc
IOC
voc
voc
voc
IOC
soc
soc
voc
SYSTEM
=====
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC.TNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC.TNC
CWS.NTNC.TNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC.TNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
SIZE
==========
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
Phase ll-b Rule
Aldicarb4
	 — 	 = 	
I Aldicarb sulfone4
I Aldicarb sulfoxide4
j Barium
SOC
SOC
SOC
IOC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
All sizes
All sizes
All sizes
All sizes

-------
CONTAMINANT
Pentachlorophenot
TYPE
soc
SYSTEM
CWS.NTNC
SIZE
All sizes
PhaseVRufe - ;;-.-:
Antimony
Benzo(a)pyrene (PAH)
Beryllium
Cyanide
Dalapon
Dichloromethane
Di(2-ethylhexyl)adipate
Di(2-ethylhexyl)phthalate
Dinoseb
Diquat
Endothall
Endrin
Glyphosate
Hexachlorobenzene
Hexachlorocyclipentadiene
Nickel
Oxamyl (Vydate)
Pidoram
Simazine
2,3,7,8-TCDD (Dioxin)
Thallium
1 ,2,4-Trichlorobenzene
1 , 1 ,2-Trichloroethane
IOC
soc
IOC
IOC
soc
voc
soc
soc
soc
soc
soc
soc
soc
soc
soc
IOC
soc
soc
soc
soc
IOC
voc
voc
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
CWS.NTNC
All sizes
All sizes
-All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
All sizes
Radionuclides Rule5
Beta particles and photon
emitters
Gross alpha particle activity
Rad
Rad
CWS
CWS
• > 100,000 persons
« using surface water
« deemed to be vulnerable
by the State
All sizes

-------
CONTAMINANT
Radium 226 & Radium 228
(combined)
TYPE
Rad
SYSTEM
cws
SIZE
All sizes
Surface Water Treatment Rule , " , X- • , , , "1-, ,,
Glardia Lamblia
Heterotrophic plate count
Leglonella
Turbidity
Viruses (enteric)
Total Cdiform Rule
Total Trihalomethanes Rule
(TTHM)
Bact
Bact
Bact
Ind
Micro
Bact
DBF
CWS.NTNC.TNC
CWS.NTNC.TNC
CWS.NTNC.TNC
CWS.NTNC.TNC
CWS.NTNC.TNC
CWS,NTNC,TNC
cws
All sizes
All sizes
All sizes
Ail sizes
All sizes
Alf sizes
• > 10,000
« add disinfectant
(oxidant)
1)     Bact means bacteria.
       DBF means Disinfection Byproduct.
       Ind means indicator.
       IOC means Inorganic Contaminant.
       Micro means microbiological contaminant.
       Rad means radionuclide.
       SOC means Synthetic Organic Contaminant.
       VOC means Volatile Organic Contaminant.

2)     CWS means Community Water System.
       NTNC means Non-Transient, Non-Community water system.
       TNC means Transient, Non-Community water system.

3)     A revised version of the Arsenic Rule will be proposed November 1995 and promulgated
       November 1997.

4)     Regulation currently not in effect for aldicarb, aldicarb sulfone and aldicarb sulfoxide.

5)     There is a proposed Radionuclides Rule that could change these levels.

-------
                        APPENDIX B:





TABLE 1: Contaminants Regulated Under the Safe Drinking Water Act





            TABLE 2:  Final and Effective Dates by Rule

-------

-------
                          Appendix B
Table 1: Contaminants Regulated Under the Safe Drinking Water Act1
                      Alphabetical by Rule
CONTAMINANT
Arsenic Rule*
1 Fluoride Rufe
MCLG
(mg/l)
none3
4.0
MCL
(mg/l)
0.05
4.0
Lead and Copper Rule
Copper
Lead
1.3
zero
TT
TT
POTENTIAL HEALTH EFFECTS I
Dermal and nervoy$ system effects
Skeletal fluorosis

Gastrointestinal effects
Cancer (Group B2), kidney, central &
peripheral nervous system effects
Phase 1 Rule (VQCs)
Benzene
Carbon tetrachloride
p-Dichlorobenzene
1 ,2-Dichloroethane
1 ,1 -Dichloroethylene
1,1,1-Trichloroethane
Trichloroethylene
Vinyl chloride
zero
zero
0.075
zero
0.007
0.2
zero
zero
0.005
0.005
0.075
0.005
0.007
0.2
0.005
0.002
Cancer (Group A)
Cancer (Group B2)
Kidney effects, possible carcinogen
Cancer (Group B2)
Liver, kidney effects, possible
carcinogen (Group C)
Liven nervous system effects
Cancer (Group B2)
Cancer (Group A)
Phase II Rule
Acrylamide
Alachlor
Asbestos (fiber >1Q microns)
Atrazine
Carbofuran
Cadmium
Chlorobenzene
Chlordane
Chromium (total)
Dibromochloropropane
(DBCP)
	 , 	
o-Dichlorobenzene
zero
zero
7MFL4
0.003
0.04
0.005
0.1
zero
0.1
zero
0.6
TT
0.002
7MFL
0.003
0.04
0.005
0.1
0.002
0.1
0.0002
0.6
Cancer (Group B2), nervous system
effects
Cancer (Group B2)
Possible carcinogen by ingestion
Liver, kidney, lung, cardiovascular
effects, possible carcinogen (Group C)
Nervous system, reproductive system
effects
Kidney effects
Nervous system, liver effects
Cancer (Group B2)
Liver, kidney, circulatory system
effects
Cancer (Group B2)
Liver, kidney, blood cell effects

-------
CONTAMINANT
cis-1 ,2-DichIoroethylene
trans-1 ,2-Dichloroethylene
1 ,2-Dichloropropane
2,4-D
Ethylbenzene
I Ethylene dibromide (EDB)
I Eplchlorohydrin
Heptachlor
I Heptachlor epoxide
Lindane
Mercury
	 	 	
Methoxychlor
I Nitrate
[— — 	 — — 	
Nitrite
Nitrate/Nitrite Combined
PCBs
Selenium
I Styrene
| Tetrachioroethyiene
II Toluene
I Toxaphene
II 2,4,5-TP
| Xylenes (total)
MCLG
0.07
0.1
zero
0.07
0.7
zero
zero
zero
zero
0.0002
0.002
0.04
10
1
10
zero
0.05
0.1
zero
1
zero
0.05
10
MCL
0.07
0.1
0.005
0.07
0.7
0.00005
TT
0.0004
0.0002
0.0002
0.002
0.04
10
1
10
0.0005
0.05
0.1
0.005
1
0.003
0.05
10
POTENTIAL HEALTH EFFECTS
Liver, kidney, nervous system, circulatory
system effects
Liver, kidney, nervous system, circulatory
system effects
Cancer (Group B2)
Liver, kidney effects
Liver, kidney, nervous system effects
Cancer (Group B2)
Cancer (Group B2)
Cancer (Group B2)
Cancer (Group B2)
Liver, kidney, nervous system, immune
system, circulatory system effects
Kidney, central nervous system effects
Developmental, liver, kidney, nervous system
effects
Methemoglobinemia (Blue Baby Syndrome)
Methemoglobinemia (Blue Baby Syndrome)
Methomoglobinemia (Blue Baby Syndrome)
Cancer (Group B2)
Nervous System Effects
Liver, nervous system effects, possible
carcinogen
Cancer
Liver, kidney, nervous system, circulatory
system effects
Cancer (Group B2)
Liver, kidney effects
Liver, kidney, nervous system effects
|] Phase Il-b Rule
I Aldicarb5
I Aldicarb sulfone5
Aldicarb sulfoxide5
Barium
I Pentachlorophenol
0.001
0.001
0.001
2
zero
0.003
0.002
0.004
2
0.001
Nervous system effects
Nervous system effects
Nervous system effects
Blood pressure effects
Cancer (Group B2)

-------
CONTAMINANT
MCLG
MCL
POTENTIAL HEALTH EFFECTS
Phase V Rule
Antimony
Benzo(a)pyrene (PAH)
Beryllium
Cyanide
Dalapon
Dichloromethane
Di(2-ethylhexyl)adipate
Di(2-ethylhexyl)phthalate
Dinoseb
Diquat
Endothall
Endrin
Glyphosate
Hexachlorobenzene
Hexachlorocyclipentadiene
Nickel
Oxamyl (Vydate)
Picloram
Simazine
2,3,7,8-TCDD (Dioxin)
Thallium
1 ,2,4-Trichlorobenzene
1 , 1 ,2-Trichloroethane
0.006
zero
0.004
0.2
0.2
zero
0.4
zero
0.007
0.02
0.1
0.002
0.7
zero
0.05
0.1
0.2
0.5
0.004
zero
0.0005
0.07
0.003
0.006
0.0002
0.004
0.2
0.2
0.005
0.4
0.006
0.007
0.02
0.1
0.002
0.7
0.001
0.05
0.1
0.2
0.5
0.004
3 X 10'8
0.002
0.07
0.005
Decreased longevity, blood effects
Cancer (Group B2)
Cancer (Group B2); bone and lung
effects
Thyroid, central nervous system
effects
Kidney, liver effects
Cancer (Group B2)
Developmental effects
Cancer (Group B2)
Thyroid, reproductive effects
Ocular, liver, kidney effects
Liver, kidney, gastrointestinal effects
Liver, kidney, heart effects
Liver, kidney effects
Cancer (Group B2)
Kidney, stomach effects
Liver effects
Kidney effects
Liver, kidney effects
Body weight and blood effects,
possible carcinogen (Group C)
Cancer (Group B2)
Liver, kidney, brain, intestine effects
Liver, kidney effects
Liver, kidney effects, possible
carcinogen (Group C)
Radionuclides Rule8
Beta particles and photon
emitters
Gross alpha particle activity
Radium 226 & Radium 228
(combined)
none3
none3
none3
4
mrem/yr
15 pCi/l
5 pCi/l
Cancer (Group A)
Cancer (Group A)
Cancer (Group A)

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CONTAMINANT
MCLG
MCL
POTENTIAL HEALTH EFFECTS
Surface Water Treatment Rule , "' " '
Glardla lamblla
Heterotrophic Plate Count
Leglonella
Turbidity
Viruses (enteric)
Total Coliform Rule »
Total Trihalomethanes Rule (TTHM)
zero
N/A
N/A
N/A
zero
zero
none3
TT
TT
TT
TT
TT
5,0%7
o,to
Gastro-enteric disease
Indicator of treatment effectiveness
and water quality
Pneumonia-like effects
Interferes with disinfection, indicator
of filtration performance
Gastro-enteric effects, respiratory
disease and other diseases (e.g.,
hepatitis, myocarditis)
Indicator of gastro-enteric infections
Cancer (Group 82)
1)     Source:  U.S. Environmental Protection Agency.  Technical and Economic Capacity of
       States and Public Water Systems to Implement Drinking Water Regulations: Report to
       Congress (EPA 810/R-93-Q01). September 1993. pp. 34-37.

2)     A revised versio'n of the Arsenic Rule will be proposed November 1995 and promulgated
       November 1997  (a court-ordered deadline).

3)     The MCLG for this contaminant was withdrawn and is currently under review.

4)     MFL = Million fibers per liter.

5)     Regulation currently not in effect for aldicarb, aldicarb sulfone and aldicarb sulfoxide. EPA
       plans to  repropose these levels in 1994.

6)     There is a proposed Radionuclides Rule that could change these levels. The court-ordered
       promulgation date is April 1995.

7)     No more than 5.0% samples total coliform-positive during month.  (For PWSs that collect
       <40 samples/month, no  more than one sample total coliform-positive).

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                         APPENDIX B

               Table 2: Final and Effective Dates by Rule
RULE1
Arsenic Rule2
Ruoride Rule
Lead and Copper Rule
Phase I Rule
Phase II Rule
Phase ll-b Rule
Phase V Rule
Radionuclides Rule3
Surface Water Treatment Rule
Total Cdliform Rule
Total Trihalomethanes Rule
FINAL DATE
December 24, 1975
April 2, 1986
June 7, 1991
July 8, 1987
January 30, 1991
Julyl, 1991
July 17, 1992
July 9, 1976
June 29, 1989
June 29, 1989
November 29, 1979
EFFECTIVE
DATE
June 24. II 977
October 2, 1987
December?, 1992
January 9, 1989
July 30, 1992
January 1, 1993
January 17, 1994
June 24, 1977
December 31, 1990
December 31, 1990
November 29, 1981
for systems serving
> 75,000;
November 29, 1983
for systems serving
10,001 - 74,999
1)     Final Rules only.  Proposed Rules and Rules scheduled for proposal are not included in this table.

2)     A revised version of the Arsenic Rule is expected to be proposed November 1995 and promulgated
       November 1997 (a court-ordered deadline).

3)     There is a proposed Radionuclides Rule that could revise this rule.  The court-ordered deadline for
       promulgation is April 1995.

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APPENDIX C: DRINKING WATER PRIORITY LIST

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                                        Appendix C

                        Drinking Water Priority List Contaminants
                        Published January 14,1991 (56 FR 1470)
 Acrylonitrile
 Aluminum
 Asulam
 Bentazon
 Boron
 Bromacil
 Bromobenzene
 Bromochloroacetonitrile
 Bromodichloromethane
 Bromoform
 Bromomethane
 Chloramines
 Chlorate
 Chlorination/Chloramination by-products
        (Misc.), e.g., Haloacetic acids,
        Haloketones, Chloral hydrate, MX-2
        [3-chIoro-4-(dichloromethyl)-5-
        hydroxy-2 (5H)-furanone]t N-
        Organochloramines
 Chlorine
 Chorine dioxide
 Chlorite
 Chloroethane
 Chloroform
 Chloromethane
 Chloropicrin
 o-Chlorotoluene
 p-Chlorotoluene
 Cryptosporidium
 Cyanazine
 Cyanogen chloride
 Cyromazine
 DCPA (and its acid metabolites)
 Dibromoacetonitrile
 Dibromochloromethane
 Dibromomethane
 Dicamba
Dichloroacetonitrile
 1,3-Dichlorobenzene
Dichlorodifluoromethane
 1,1 -Dichloroethane
2,2-Dichloropropane
1,3-Dichloropropane
 1,1 -Dichloropropene
 1,3-Dichloropropene
 2,4-Dinitropneraol
 2,4-Dinitrotoluene
 2,6-Dinitrotoluene
 1,2-Diphenylhydrazine
 Ethylenethioureia
 Fluorotrichloromethane
 Fomesafen
 Hexachlorobutadiene
 Hexachloroethane
 Hypochlorite ion
 Isophorone
 Lactofen/Acifluorfen
 Manganese
 Metalaxyl
 Methomyl
 Methyl ethyl ketone
 Methyl isobutyl ketone
 Methyl t-butyl either
 Metolachlor
 Metribuzin
 Molybdenum
 Naphthalene
 Nitrobenzene
 Ozone by-products,
       e.g., Aldehydes, Epoxides,
       Peroxides, Nitrosamines, Bromate,
       lodate
 Parathion degradation product
       (4-Nitrophenol)
 Prometon
 Strontium
 2.4,5-T
 1,1,1,2-Tetrachloroethane
 1,1,2,2-Tetrachloroethane
Tetrahydrofuran
Thiodicarb
Trichloroacetonitrile
 1,2,3-Trichloropropane
Trifluralin
Vanadium
Zinc

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APPENDIX D: SECONDARY DRINKING WATER REGULATIONS

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                                   Appendix D

                   Secondary Drinking Water Regulations1
CONTAMINANT
Aluminum
Chloride
Color
Copper
Corrosivity
Fluoride
Foaming Agents
Iron
Manganese
Odor
PH
Silver
Sulfate
Total dissolved solids (TDS)
Zinc
SMCL
(mg/i)
0.05-0.2
250
15 color units
1
non-corrosive
2.0
0.5
0.3
0.05
3 threshold odor
number
<6.5 - >8.5 pH
0.1,
250
500
5
CONTAMINANT EFFECTS
Discoloration of water
Taste, corrosion of pipes
Discoloration of water
Taste, staining of porcelain
Aesthetic and health related (corrosive
water can leach pipe materials, such as
lead, into drinking water).
Dental fluorosis (a brownish
discoloration of the teeth)
Aesthetic
Taste, staining of laundry
Taste, staining of laundry
Aesthetic
Water is too corrosive
Argyria (discoloration of the skin)
Taste, laxative effects
Taste and possible relation between low
hardness and cardiovascular disease,
also an indicator of corrosivity (related to
lead levels in water). Can damage
plumbing and limit effectiveness of
soaps and detergents.
Taste
1)    Source: U.S. Environmental Protection Agency. Fact Sheet: National Secondary Drinking
     Water Standards (EPA 570/9-91-019FS). September 1991.
                                                •&U.S. GOVERNMENT PRINTING OFFICE: 1995 - £15-003/01094

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