United St»»» EPA $1
-------
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-mandatoiy water quality standards for 15
contaminants. EPA does not 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
SMCL.
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. TTiese 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.
¦ Standards related to odor and taste:
Chloride, Copper, Foaming Agents, Iron,
Manganese pH, Sulfate, Threshold Odor
Number (TON), Total Dissolved Solids,
Zinc.
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 metals 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.
¦ 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.
¦ Standards related to foaming: Foaming
Agents.
-------
Cosmetic Effects
Skin discoloration is a cosmetic effect related to
silver ingestion. This effect, called argyria, does not
impair body function, and has never been found to
be caused by drinking water in the United States. A
standard has been set however, because silver is
used as an antibacterial agent in many home water
treatment devices, and so presents a potential
problem which deserves attention
e 1. Secondary Maximum
ntaminant Levels
intaminanf
Standard related to this effect. Silver.
Tooth discoloration and/or pitting is caused by
excess fluoride exposures during the formative
period prior to eruption of the teeth in children. The
secondary standard of 10 mg/L is intended as a
guideline for an upper boundary level in areas which
have high levels of naturally occurring fluoride. It is
not intended as a substitute for the lower concentra-
tions (0.7 to 1.2 mg/L) which have been recom-
mended for systems which add fluoride to their
water. The level of the SMCL was set based upon a
balancing of the beneficial effects of protection from
tooth decay and the undesirable effects of excessive
exposures leading to discoloration.
¦ Standard related to this effect. Fluoride.
Technical Effects
Corrosivity, and staining related to corrosion,
not only affect the aesthetic quality of water, but may
also have significant economic implications. Other
effects of corrosive water, such as the corrosion of
iron and copper, may stain household fixtures, and
impart objectionable metallic taste and red or blue-
green color to the water supply as well. Corrosion of
distribution system pipes can reduce water flow.
¦ Standards related to corrosion and stain-
ing: Chloride, Copper, corrosivity. Iron,
Manganese, pH, Total Dissolved Solids.
Zinc.
Scaling and sedimentation are other processes
which have economic impacts. Scale is a mineral
deposit which builds up on the insides of hot water
pipes, boilers, and heat exchangers, restricting or
even blocking water flow. Sediments are loose
deposits in the distribution system or home plumb-
ing.
¦ Standards related to scale and sediments'.
Iron, pH Total Dissolved Solids, Alumi-
num.
Noticeable
Secondary Effects above the
MCL Secondary MCL
Aluminum
Chloride
Color
Copper
0.05 to 0.2 mg/L*
250 mg/L
15 color units
1.0 mg/L
Corrosivity Non-corrosive
Fluoride
Foaming agents
Iron
Manganese
2,0 mg/L
0.5 mg/L
03 mg/L
staining
0.05 mg/L
colored water
salty taste
visible tint
metallic taste
blue-green staining
metallic taste
corroded pipes/
fixtures naming
tooth discoloration
frothy, cloudy
bitter taste
odor
rusty color
sediment
metallic laste
reddish or orange
Odor
PH
3 TON
(threshold odor number)
6.5 8.5
Silver
Sulfate
Total Dissolved
Solids (TDS)
0 1 mg/L
250 mg/L
500 mg/L
black to brown color
black staining
bitter metallic taste
"rotten-egg", musty
or
chemical smell
lowpH
bitter metallic
taste
corrosion
highpH:
slippery feel
soda taste
deposits
skin discoloration
greying of the white
part of the
seye
parte
salty taste
hardness
deposits
colored water
staining
salty taste
metallic taste
Zinc 5 mg/L
* mg/L is milligrams of substance per liter
of water
-------
How can these Problems be
Corrected?
Although state health agencies and public
water systems often decide to monitor and treat
their supplies for secondary contaminants, federal
regulations do not require them to do this. Wt»o«
waatdftiy contaminants arc a problem, the types of
removal technologies discussed below iw oorma-
live actions which the water supplier cjii tab Ttwy
~re usually effrttive depending upon the overall
nature ot the water supply.
Corrcr,urn control is perhaps the single most
cost-effective method a system can uw to treat for
(ton, copper and zinc due to the significant benefit 1
in fl) reduction of contaminants at the oonsumef *
tap, (2) cost savings duo to extending the useful lit-
of water mains and service lines, 13) energy saving
from transporting water more easily through
smoother, uncomxled pipes, and (4) reduced water
low*® t hrough leaking or broken main* or other
plumbing, This ttvvtmcnt it unod iu control the
oddity, alkalinity or other waiter qualltk*
-------
¦ F1FTII. support rale increase* for your
local wafer supplier, where necessary, to
upgrade your supplier's treatment
facilities to meet drinking water standouts
¦ FINALLY, If you have a private welJ
and you think (hat the wril may be near a
sowce of contamination or may have been
contaminated HAVE YOUR WATER
TESTED by A certified laboratory A li si
of certified labs is available- from ycnir
slate's laboratory certification officer. A
tin of the certification officers can be
obtained from the Safe Drinking Water
Hotline.
For More Information
For more inform anon on secondary contami-
nants, write or call the EPA Ask for a ltet of the*
primarv and secondary contaminant*, About
monitoring requirements for the*;. and /or • Iim or
the health advisories available for these contami-
nants.
Write:
U.S. Environmental Protection Agency
Office of Ground Water and Drinking Waiter
(WH-5S0A)
401 M Street, SW
Washington, DC 20460
Or Call:
The Safe Drinking Wat® Hotline
800-426-4791
For a good general overview of the t'ubllt
water "-upply program and some Insight* into the
citizen's role, write or call to obtain thee three
booklets;
Safety
------- |