New Report Focuses on Disinfection Byproducts in Drinking Water

The Environmental Working Group issued a report Feb. 27 focused on disinfection byproducts in drinking water.

The report, called “Water Treatment Contaminants: Toxic Trash in Drinking Water,” suggests that consumers are being exposed to disinfection byproducts, especially trihalomethanes (THMs), at greater concentrations than most people realize and questions the safety of current drinking water standards for THMs and other byproducts.

Disinfection byproducts, including THMs and others such as haloacetic acids and nitrosamines, can form when chemicals used to disinfect drinking water combine with naturally occurring organic and inorganic materials in water. The U.S. Environmental Protection Agency requires the use disinfectants such as chlorine to treat drinking water from both surface and groundwater sources.

The EWG report features data from 201 large water systems in 43 states, including California. The data is based on average levels of THMS and haloacetic acids for the year 2011 as reported in 2012 Consumer Confidence Reports. Levels from 32 systems in California are included.

Only one of the systems studied by EWG – a system in Iowa – reported a level that exceeded EPA standards for THMs in drinking water.

Disinfection of drinking water is considered one of the most significant public health advances of the 20th century. Chlorine has been in use as a disinfectant in the United States since 1908 and is viewed as major factor in reducing epidemics of typhoid, cholera and other diseases that were common at one time.

EPA regulates disinfection byproducts under standards that were made significantly more stringent in the Stage 2 Disinfectant and Disinfection Byproduct Rule(DBPR) of 2006. The Stage 2 DBPR was the latest in a series of regulations designed to reduce disinfection byproducts without compromising disinfection.  The rules reflect a broad-based stakeholder consensus that included consumer advocates, state regulators, and public health officials. The Stage 2 DBPR is implemented in California by the Department of Public Health.

The complete EWG report is available here.   

The American Water Works Association has consumer information on disinfection byproducts here.