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Hazardous Chlorination Byproducts in Drinking Water

In May 2007 the Environmental Working GroupExit Site funded tap water tests in the District of Columbia, revealing excessive levels of toxic by-products caused by chlorine and chloramines, beyond the annual federal health safety limits. These primary chlorine compounds are used to kill pathogens and bacteria from water taken from the Potomac River. Theses test results point to huge difficulties that confront water utilities, working to provide tap water, free of deadly bacteria and pathogens, while at the same time faced with limiting the damagingside effects caused chlorine and chloramines by-products.

Are Chloramines safer than Chlorine?

Due to the EPA's set legal limits, in particular THMs, many water utilities, including the District of Columbia and Northern Virginia, have upgraded to the use of chloramines, which work to produce lower levels of disinfection byproducts, including THMs and HAAs. However, chloramines lack the disinfection strength of free chlorine. Often water utilities that use chloramines, periodically perform a "chlorine burn," removing sludge from the pipes, but also temporarily increases the amount of disinfection by-products presented on the drinking water. This year the water utility's chlorine burn was performed during April 7 and May 7.

Free Chlorine By-Products: THM - Trihalomethanes and HAAs - Haloacetic AcidsExit Site

Chloramine By-Products: Reduced THM - Trihalomethanes and HAAs - Haloacetic Acids

The US Environmental Protection Agency classifies HAAs as carcinogenic to humans and animals. Peer-reviewed studies have identified adverse reproductive and developmental effects, and the ability to damage DNA. The state of Oregon has warned that long term exposure to HAAs at levels equal to those found in DC tap water could cause injury to the brain, nervous system, the eyes, and the reproductive system.

Filter Recommendations based on recent testing

The Environmental Working Group recommends using, "carbon filters for all 1.1 million consumers of tap water from the Washington Aqueduct in Washington DC and Northern Virginia. Carbon filtration of tap water will dramatically lower levels of toxic disinfection byproducts."

"Carbon filtration is also 10 to 20 times less expensive than bottled water, and does not produce the waste and pollution associated with the packaging and transport of bottled water."

EPA scientists have identified600 disinfection by-products in chlorinated drinking water

Even though chlorinated drinking water contains 600 disinfection by-products, the EPA has set legal limits in drinking water for only 11 of those by-products. The legal limits for HAAs and THMs, are established by balancing health, treatment cost and feasibility.

Other Toxic Chlorine By-Products Include:

Haloacetic acids

Disinfectants react with organic and inorganic substancespresent in the water to produce a variety of disinfection by-products or DBPs. This DBPs fact sheet describes the different types of DBPs and the potential health risks associated with each of them.

Protecting drinking water at the source

If the Potomac River were less polluted as it flowed into the utility's intake pipe, less chlorine and chloramines would be needed, and levels of disinfection by-products would be lower as a result.

The primary source of agriculture pollutants include, manure, fertilizer, pesticides and soil run-off, finding there way into drinking water supplies and watersheds.

Related Reading:

Specific contaminates found in drinking water.

Updated: Sept 16 2015