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Chloramine

Recently San Francisco Public Utility Commision (SFPUC) Exiting EPA
(disclaimer) changed from using free chlorine to chloramine in its
drinking water transmission pipes. Some people are concerned for
possible public health implications and for reported effects on fish
and amphibians.

Using chloramine to disinfect drinking water is a common standard
practice among drinking water utilities. A number of utilities have
made this switch from chlorine to chloramines to enhance water safety
and compliance with drinking water health standards. For example, the
East Bay Municipal Utility District (EBMUD) Exiting EPA (disclaimer),
which serves drinking water to customers in parts of the greater San
Francisco Bay area, switched from chlorine to using chloramine in
February, 1998.
Background information on chloramines

Chlorine has been safely used for more than 100 years for disinfection
of drinking water to protect public health from diseases which are
caused by bacteria, viruses and other disease causing organisms.
Chloramines, the monochloramine form in particular, have also been
used as a disinfectant since the 1930's. Chloramines are produced by
combining chlorine and ammonia. While obviously toxic at high levels,
neither pose health concerns to humans at the levels used for drinking
water disinfection.

Chloramines are weaker disinfectants than chlorine, but are more
stable, thus extending disinfectant benefits throughout a water
utility's distribution system. They are not used as the primary
disinfectant for your water. Chloramines are used for maintaining a
disinfectant residual in the distribution system so that disinfected
drinking water is kept safe. Chloramine can also provide the following
benefits:

* Since chloramines are not as reactive as chlorine with organic
material in water, they produce substantially lower concentrations of
disinfection byproducts in the distribution system. Some disinfection
byproducts, such as the trihalomethanes (THMs) and haloacetic acids
(HAAs), may have adverse health effects at high levels. These
disinfection byproducts are closely regulated by EPA. EPA recently
reduced the allowable Maximum Contaminant Levels for total THMs to 80
ug/L and now limit HAAs to 60 ug/L. The use of chlorine and
chloramines is also regulated by the EPA. We have Maximum Residual
Disinfectant Levels of 4.0 mg/L for both these disinfectants. However,
our concern is not from their toxicity, but to assure adequate control
of the disinfection byproducts.
* Because the chloramine residual is more stable and longer
lasting than free chlorine, it provides better protection against
bacterial regrowth in systems with large storage tanks and dead-end
water mains.
* Chloramine, like chlorine, is effective in controlling biofilm,
which is a slime coating in the pipe caused by bacteria. Controlling
biofilms also tends to reduce coliform bacteria concentrations and
biofilm-induced corrosion of pipes.
* Because chloramine does not tend to react with organic
compounds, many systems will experience less incidence of taste and
odor complaints when using chloramine.

Other concerns with chloramines in drinking water

Chloramines, like chlorine, are toxic to fish and amphibians at levels
used for drinking water. Unlike chlorine, chloramines do not rapidly
dissipate on standing. Neither do they dissipate by boiling. Fish
owners must neutralize or remove chloramines from water used in
aquariums or ponds. Treatment products are readily available at
aquarium supply stores. Chloramines react with certain types of rubber
hoses and gaskets, such as those on washing machines and hot water
heaters. Black or greasy particles may appear as these materials
degrade. Replacement materials are commonly available at hardware and
plumber supply stores.
For more information

Contact the Region 9 Drinking Water Office at (415) 972-3547. Your
drinking water utility may also have information about your specific
service.

Contact the San Francisco Public Utility Commision Exiting EPA
(disclaimer) for more information on San Francisco's conversion to
chloramines.