United Steles     EPA 81 0/K-92-OG1
       Environmental Protection    July 1992

       Office of Water (WH-550A)
oEPA Secondary
       Drinking Water
       Guidance for
             7-,/y Printed on Recycled Paper

       United States     EPA 81O/K-92-001
       Environmental Protection    July 1992
       Office of Water (WH-550A)
oEPA Secondary
       Drinking Water

       Guidance for
             ^/C Printed on Recycled Paper

What are Secondary Standards?

     The U.S. Environmental Protection Agency
(EPA) has established National Primary Drinking
Water Regulations that set mandatory water quality
standards for drinking water contaminants. These
are enforceable standards called "maximum
contaminant levels" or "MCLs", which are estab-
lished to protect the public against consumption of
drinking water contaminants that present a risk to
human health. An MCL is the maximum allowable
amount of a contaminant in drinking water which is
delivered to the consumer.
     In addition, EPA has established National
Secondary Drinking Water Regulations that set
non-mandatory water quality standards for 15
contaminants. EPA does riot enforce these "second-
ary maximum contaminant levels" or "SMCLs."
They are established only as guidelines to assist
public water systems in managing their drinking
water for aesthetic considerations, such as taste,
color and. odor. These contaminants are not
considered to present a risk to human health at the
Why Set Secondary Standards?

      Since these contaminants are not health
threatening at the SMCL, and public water systems
only need test for them on a voluntary basis, then
why it is necessary to set secondary standards?
      EPA believes that if these contaminants are
present in your water at  levels above these stan-
dards, the contaminants  may cause the water to
appear cloudy or colored, or to taste or smell bad.
This may cause a great number of people to stop
using water from their public water system even
though the water is actually safe to drink.
      Secondary standards are set to give public
water systems some guidance on removing these
chemicals to levels that are below what most people
will find to be noticeable.
What problems are caused by
THESE contaminants?	_____

     There are a wide variety of problems related
to secondary contaminants. These problems can be
grouped into three categories: Aesthetic effects -
undesirable tastes or odors; Cosmetic effects - effects
which do not damage the body but are still undesir-
able; and Technical effects - damage to water equip-
ment or reduced effectiveness of treatment for other
contaminants. The secondary MCLs related to each
of these effects are given in Table 1.

     Aesthetic Effects
     Odor and Taste are useful indicators of water
quality even though odor-free water is not necessar-
ily safe to drink. Odor is also an indicator of the
effectiveness of different kinds of treatment.
However, present methods of measuring taste and
odor are still fairly subjective and  the task of
identifying an unacceptable level for each chemical
in different waters requires more study. Also, some
contaminant odors are noticeable even when
present in extremely small amounts. It is usually
very expensive and often impossible to identify,
much less remove, the odor-producing substance.

    H  Standards related to  odor and taste:
        Chloride, Copper, Foaming  Agents, Iron,
        Manganese pH, Sulfate, Threshold Odor
        Number (TON), Total Dissolved Solids,

     Color may be indicative of dissolved organic
material, inadequate treatment, high disinfectant
demand and the potential for the production of
excess amounts of disinfectant by-products.
Inorganic contaminants such as rnetals are also
common causes of color. In general, the point of
consumer complaint is variable over a range from 5
to 30 color units, though most people find color
objectionable over 15 color units. Rapid changes in
color levels may provoke more citizen complaints
than a relatively high, constant color level.

    H  Standards  related to  color. Aluminum,
        Color, Copper, Foaming Agents, Iron,
        Manganese, Total Dissolved Solids.

     Foaming is usually caused by detergents and
similar substances when water has been agitated or
aerated as in many faucets. An off-taste described
as oily, fishy, or perfume-like is commonly associ-
ated with foaming. However, these tastes and odors
may be due to the breakdown of waste products
rather than the detergents themselves.

    H   Standards related to foaming: Foaming

        FIFTH, support rate increases for your
        local water supplier, where necessary, to
        upgrade your supplier's treatment
        facilities to meet drinking water standards.
        FINALLY, if you have a private well
        and you think that the well may be near a
        source of contamination or may have been
        contaminated - HAVE YOUR WATER
        TESTED by a certified laboratory. A list
        of certified labs is available from your
        state's laboratory certification officer. A
        list of the certification officers can be
        obtained from the Safe Drinking Water
For More Information

     For more information on secondary contami-
nants, write or call the EPA. Ask for a list of the
primary and secondary contaminants, about
monitoring requirements for these, and for a list of
the health advisories available for these contami-
U.S. Environmental Protection Agency
Office of Ground Water and Drinking Water
401 M Street, SW
Washington, DC 20460
        Or Call:
The Safe Drinking Water Hotline
     For a good general overview of the public
water supply program and some insights into the
citizen's role, write or call to obtain these three
     Safety on Tap: A Citizen's Drinking Water
Handbook. Available from League of Women Voters
of the United States, 1730 M Street, NW, Washing-
ton, DC 20036. (202) 429-1965. Publication  #840.
     Drinking Water: A Community Action Guide.
Available from CONCERN, Inc., 1794 Columbia
Road, NW, Washington, DC  20009. (202)328-8160.
      "7s Your Drinking Water Safe?" EPA Publica-
tion 570/9-91-005. June 1989. Available from
USEPA Office of Water (WH-550) 401 M St., SW,
Washington DC, 20460

    -identify your local public water
    '*        a water bill, the name,
             nne number of your

    £l^biM*» Contact your
        artment—Ihey should know.
     UN|), contact your local public
     system. Inquire about your
     ier's monitoring for secondary

i Hvered to the public meet these
lEllMCLs? If you have not yet received

  ^a>,if,ou revive a pubUcnoWe
          m. who is indicated in the
                 in unavailable,
               state drinking water
         'OT yVur'local health department.
          I, contact your state drinWng

             ride the information you
              . Your state drintang