This is a fact sheet about a chemical that may be found in some public or
private drinking water supplies. It may cause health problems if found
in amounts greater than the health standard set by the United States
Environmental Protection Agency (EPA).
What is Chloramine and are there any negative health effects from its presence in drinking water?
Chloramine is formed as a result of the reaction between applied chlorine and ammonia present in the natural
water or ammonia that has been added to react with chlorine so that a combined chlorine (chloramine) residual
will be formed. This practice has been used in municipal water treatment for over 70 years.
Chloramine is used principally in systems requiring a reduction in tastes and odors, or a reduction in
disinfection byproducts, such as trihalomethanes (THMs). Particularly where the water supply contains
phenol, free chlorine readily reacts to form chlorophenol, which has a very disagreeable taste and odor.
More recently, many public water systems have found that chloramine can be used to reduce the THM level
in their water.
The primary disadvantage of chloramine is that it is a much weaker and slower acting disinfectant than
free chlorine. It is particularly weak for inactivating certain viruses. In water systems that use
chloramine as the principal disinfectant, ammonia is added at a point downstream from the initial
chlorine application so that microorganisms, including viruses, will be exposed to the free chlorine for
a short period before the chloramine is formed.
Hospitals and kidney dialysis centers must be alerted when chloramines are used for water supply
disinfection. Cases of chloramine-induced hemolytic anemia in patients have been reported when
their dialysis water was not appropriately treated. Otherwise, we know of no ill-health effects
associated with the ingestion of chloraminated drinking water.
Chloramines can be removed from water with very low flow rates (5 to 10 minutes contact time)
through shell-base activated carbon, followed by mineral zeolite media for residual ammonia adsorption.
Note: This fact sheet is part of a larger
publication adapted from The Water Quality Association: Water Quality Answers.
Recently San Francisco Public Utility Commision (SFPUC) 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), 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.
Some people who use drinking water containing chloramines well in excess of EPA's standard could experience
irritating effects to their eyes and nose. Some people who drink water containing chloramines well in excess of
EPA's standard could experience stomach discomfort or anemia.
Note: This fact sheet is part of a larger
publication adapted from U.S. EPA publication: EPA National Primary
Drinking Water Regulations.
Filters to Reduce Chloramine in Your Water:
ChlorPlus-10 Carbon Replacement Filter
CRFC-20BB Radial Flow Carbon Replacement Filter