United States
Environmental Protection
Agency
Office of Water
4601
EPA 570/9-91-027FS
January 1995
EPA The Phase II Rule
"Phase II
roughly doubled
the number of
drinking water
standards."
The Phase II Rule was published in the Federal Register on January 30, 1991
and July 1, 1991. It became effective in 1992 with monitoring requirements
beginning on January 1,1993. This rule set drinking water standards for 38
inorganic and organic chemicals. All community and Non-Transient, Non-
Community water systems are required to monitor for and, if necessary, treat their
supply for the regulated chemicals. Transient water systems are required to
comply with the nitrate and nitrite regulations in Phase II.
Phase II roughly doubled the number of drinking water standards. While many
of the Phase II chemicals occur in drinking water due to human activity, others are
naturally occurring. Some chemicals are only rarely found in water supplies but
are very widely used and were regulated because of the likelihood that they may
contaminate supplies in the future.
Drinking Water Standards
Maximum Contaminant Levels (MCLs): Public Water Systems are required
to make sure that the water they supply meets the MCL for each Phase II chemi-
cal. These are enforceable standards. MCLs for Phase II chemicals are listed in
Table 1.
Table 1. Phase II MCLs
Contaminant
MCL (mg/L)
Contaminant
MCL (mg/L)
Inorganics
Asbestos 7 MFL*
Barium 2
Cadmium 0.005
Chromium 0.1
Mercury 0.002
Nitrate as N 10
Nitrite as N 1
Total Nitrate/Nitrite 10
Selenium 0.05
Volatile Organics
o-Dichlorobenzene 0.6
cis-1,2-Dichloroethylene 0.07
trans-1,2-Dichloroethylene 0.1
1,2-Dichloropropane 0.005
Ethylbenzene 0.7
Monochlorobenzene 0.1
Styrene 0.1
Tetrachloroethylene 0.005
Toluene 1
Xylenes (total) 10
Pesticides and PCBs
Alachlor (Lasso)
Aldicarb (Temik)**
Aldicarb sulfoxide**
Aldicarb sulfone**
Atrazine (Atranex, Crisazina)
Carbofuran (Furadan 4F)
Chlordane
Dibromochloropropane (DBCP, Nemafume)
2,4-D (Formula 40, Weedar 64)
Ethylene dibromide (EDB, Bromofume)
Heptachlor (H-34, Heptox)
Heptachlor epoxide
Lindane
Methoxychlor (DMDT, Marlate)
Polychlorinated biphenyls (PCBs, Aroclor)
Pentachlorophenol
Toxaphene
2,4,5-TP (Silvex)
0.002
0.003
0.004
0.002
0.003
0.04
0.002
0.0002
0.07
0.00005
0.0004
0.0002
0.0002
0.04
0.0005
0.001
0.003
0.05
Treatment Techniques
Acrylamide
Epichlorohydrin
0.05% dosed at 1 mg/L
0.01% dosed at 20 mg/L
* Million fibers per liter
Public Education Fact Sheet Series
Regulation currently not in effect
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Treatment Techniques: When EPA determines that it is not economically or
technologically feasible to ascertain the level of a contaminant, EPA may set an
enforceable Treatment Technique in lieu of an MCL. Two Phase II chemicals are
controlled in this way, simply by limiting their use in other treatment processes.
Maximum Contaminant Level Goals (MCLGs): For each chemical, EPA has
set a non-enforceable health goal which water systems should try to achieve.
Water containing a chemical in an amount equal to or below its MCLG is not
expected to cause any health problems, even over a lifetime of drinking this water.
Monitoring Requirements
A major feature introduced in Phase II is its plan for synchronizing compliance
monitoring across several existing and upcoming rules. Under this Standardized
Monitoring Framework, the various monitoring frequencies for most source-
related contaminants were coordinated within compliance periods of three
years each. Some monitoring and related system activities, such as vulnerability
assessments, will occur at intervals which may span across up to three of these
three-year periods, forming a nine-year compliance cycle. The first compliance
cycle and the initial compliance period both began on January 1, 1993. Table 2
gives dates for the Framework intervals over the next several decades. Monitoring
requirements are given in Table 3.
Other features of Phase II monitoring requirements include the following:
• Sampling location - Ground water systems must sample at entry points to
the distribution system which are representative of each well after any appli-
cation of treatment. Surface water systems must sample at points within the
distribution system which are representative of each source or at entry points
to the distribution system after any application of treatment. Samples must
be analyzed by a State-certified lab.
• Initial sampling frequency - All systems must sample at a base (or mini-
mum) frequency which is specific for a contaminant or contaminant group.
The State may grant monitoring waivers (as discussed below) and may allow
a system to substitute suitable previous monitoring data ("grandfathered
data") for this initial monitoring. In the initial compliance period, the actual
year in which a system samples will be determined by the State.
• Repeat sampling frequency - In general, if a system does not detect con-
taminants in initial samples, then repeat sampling frequencies will be lower
than initial frequencies. Repeat monitoring requirements are generally the
same for all systems regardless of system size or water source.
• Trigger to increase moni-
toring - If contaminants are
detected in any sample, the
system must begin quarterly
sampling until the State
determines that subsequent
results are "reliably and
consistently" below the MCL.
At least two to four
consecutive samples must be
taken before this determina-
tion may be made. Detection
is defined separately for _. ,, _ ,. _- . .
K • Phase II Compliance Periods
Table 2. Standardized Monitoring Framework
Phase II Compliance Cycles
CYCLE 1
CYCLE 2
1993-95
1996-98
1999-2001
2002-04
2005-07
2008-10
Public Education Fact Sheet Series
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various contaminants or contaminant groups at either the MCL (for
lOCs), 50 percent of the MCL (for nitrate/nitrite), at 0.0005 mg/L (for
VOCs) or at the analytical method detection limit (for SOCs).
Monitoring waivers - Sampling frequencies may also be reduced or
eliminated if the system obtains a waiver based on: 1) previous sampling
results and/or 2) an assessment of the system's vulnerability to each
specific contaminant. There are two types of waivers based on vulnerabil-
ity assessments:
Use waiver: A system may be eligible for a waiver if it can show that a
contaminant has not been used, manufactured and/or stored within a
certain area around the system's water source. If use cannot be deter-
mined, a use waiver cannot be granted.
Susceptibility waiver: Even if a system is not eligible for a use waiver,
it may be eligible for a waiver based on its susceptibility in terms of
source protection, wellhead protection program reports, previous sample
results, environmental transport and fate of the contaminant, and
Table 3. Compliance Monitoring Requirements 1
Contaminant
Asbestos
Nitrate
Nitrite
5 Inorganics
18 VOCs
17 Pesticides
andPCBs
Unregulated
-1IOC
- 13 SOCs
Base Requirement
Ground water Surface water
1 Sample every 9 years
Annual 1 Quarterly
After 1 year < 50% of MCL, S WS
may reduce to an annual sample
1 Sample: If < 50% of MCL,
state discretion
1 Sample every Annual sample
3 years
4 Quarterly samples every 3 years
Annual after 1 year of no detects
4 Quarterly samples every 3 years
After 1 round of no detects: systems
>3300 reduce to 2 samples per year
every 3 years; systems < 3300
reduce to 1 sample every 3 years
1 Sample
4 Consecutive quarterly samples
Trigger that
Increases
Sampling
^MCL
> 50% MCL
> 50% MCL
^ MCL
> 0.0005 mg/L
Method
Detection
Limit
(MDL)
N.A.
Waivers
for Base
Requirements
YES
Based on VA1
NO
NO
YES
Based on analytical
results of 3 rounds
YES
Based on VA1
YES
Based on VA1
YES
Based on VA1
1 VA = Vulnerability Assessment
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elevated nitrate levels. If susceptibility cannot be determined, this
type of waiver cannot be granted.
• Unregulated contaminant monitoring - Phase II also contained
one-time monitoring requirements for 30 other contaminants during
the initial period which began on January 1, 1993. Systems must
take one year of quarterly samples for organic contaminants, and
one sample for inorganic contaminants. No MCLs have been set for
these contaminants, and quarterly monitoring is not required if
these chemicals are detected. However, systems do have to conduct
repeat sampling for unregulated contaminants every 5 years,
regardless of whether they detected these contaminants or not.
Systems only need to report the results of this monitoring to the
State. Systems with less than 150 service connections may request a
waiver from the State. Several of these unregulated contaminants
were regulated by the Phase V Rule. For a current list of
unregulated contaminants, refer to 40 CFR 141.40.
Treatment Options
• Permanent treatment options - For each regulated contaminant,
EPA has identified a treatment technology which is considered the
best available for achieving the MCL called the Best Available
Technology or BAT. Systems are not required to install DATs
unless they are attempting to get a variance. BATs for Phase II
chemicals are listed in Table 4.
Table 4. Phase II BATS
Organics
Volatile Organics; EDB; DBCP
Granular Activated Carbon
Packed Tower Aeration
Pesticides and PCBs
Granular Activated Carbon
Inorganics
Conventional Technologies
Coagulation/ Filtration1
Lime Softening1
Additional Technologies
Electrodialysis Reversal
Ion Exchange
Reverse Osmosis
Asbestos
Corrosion Control
Diatomite Filtration
Direct Filtration
Optional for Mercury
Granular Activated Carbon
Optional for Selenium
Activated Alumina
1 Not BAT for variance purposes for
systems with <500 service connections.
Deferred treatment options - Systems which cannot comply with an
MCL have two options for deferring installation of treatment:
- Variances allow systems to continue operating but only under and
according to a compliance schedule which sets a timeframe for installing
treatment to bring the supply into compliance. A system is eligible for a
variance only if it is already using BAT. Other factors, including health
concerns and the reasonable availability of other sources of water, must
also be considered before the State may grant a variance.
- Exemptions from MCLs are available under some conditions including
economic difficulties, regardless of whether or not BAT is being used. As
with variances though, a compliance schedule must be met, and other
factors, including health concerns and the reasonable availability of other
sources of water, must also be considered. For systems having no more
than 500 service connections, exemptions may be extended for two-year
periods if the system demonstrates an effort to take steps necessary for
achieving compliance.
Short-Term Treatment Options - As a condition of granting a variance
or exemption, States may require a system to provide its consumers with
either bottled water, point-of-use (POU) devices or point-of-entry
(POE) devices as temporary means to avoid health problems related
to exceedance of an MCL.
Non-treatment options - include regionalization, or joining with
another nearby system, development of a new source, or blending
present supplies with water from other supplies.
For More Information
Call the Safe Drinking Water
Hotline at 1-800-426-4791
Public Education Fact Sheet Series
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