DefinitionThe distribution of disinfection by products (total trihalomethane and haloacetic acid) in drinking water by community water system, population served, and year
NumeratorNumber of community water systems or estimated count of population served, by disinfection by-product concentration in drinking water.
Why Is This Important?Disinfection by products (DBPs) are formed when disinfectants (such as chlorine chemicals) used during water treatment to destroy harmful bacteria and viruses, react with natural organic matter in water. Trihalomethanes (THMs) and haloacetic acids (HAAs) are produced in the largest amounts. The level of DBPs formed after disinfection depends on the source water, type of treatment, and amount of disinfectant used.
Health risks from exposure to low levels of DBPs are not well understood. Some studies suggest that DBP exposure may increase the risk of bladder and colorectal cancers and reproductive and developmental health effects.
How Are We Doing?In order to determine the quality of water provided by community water supplies in New Jersey, the U.S Environmental Protection Agency (EPA) and the New Jersey Department of Environmental Protection (NJDEP) require mandatory, regular monitoring of treated water delivered to the public. Test results are compared to standards for drinking water quality called maximum Contaminant Levels (MCLs), the maximum permissible level of a contaminant in public drinking water based on information on health effects, treatment, analytical methods and contaminant occurrence. A complete list of the regulated contaminants and the maximum permissible concentrations allowed in drinking water are listed on NJDEP's website at:
In general, the levels of DBPs in community water systems in New Jersey have shown slight change during the last decade, as new federal and state regulations have been implemented to reduce DBP formation. Water systems using surface water sources (lakes, rivers, reservoirs) typically have higher DBP levels than water systems using groundwater wells.
What Is Being Done?Public water suppliers are required by law to monitor for regulated contaminants based on type of water system and water source, and ensure the water meets state and federal Maximum Contaminant Levels (MCLs). The test results are sent to the NJDEP. If the level of any regulated contaminant is above the MCL, additional samples are taken to confirm that a problem exists. The supplier of that water is then required to eliminate the problem by changing to another water source or by improving water treatment. The NJDEP inspects community drinking water systems and evaluates their monitoring reports for compliance with the standards. Noncompliance with a standard can result in a violation. NJDEP works with systems to ensure they notify the public and return to compliance.
Large community water systems in New Jersey are required to test for DBPs in drinking water every three months. The remaining community water systems that disinfect are required to sample annually. The average DBP levels over a 12 month period are compared to the MCLs for DBPs.
Prior to 2003, the MCL for total trihalomethanes (TTHM) in New Jersey was 100 micrograms per liter. Beginning in 2003, a new, lower MCL for TTHM of 80 micrograms per liter was phased in, beginning with large community water systems. The MCL for haloacetic acids (HAA) is 60 micrograms per liter.
Health Program InformationFor questions regarding health effects of DBPs in drinking water, contact the New Jersey Department of Health, Consumer, Environmental and Occupational Health Service, PO Box 369, Trenton, NJ 08625-0369; (609) 826-4984.
For concerns regarding Federal and State drinking water regulations and public water supply monitoring results, contact the New Jersey Department of Environmental Protection, Bureau of Safe Drinking Water, (609) 292-5550
To inquire about NJ certified laboratories for DBPs in drinking water, contact the Office of Quality Assurance at (609) 292-3950
For information on Federal drinking water regulations, health effects of DBPs in drinking water, and other water safety issues, contact the United States Environmental Protection Agency Safe Drinking Water Hotline at (800) 426-4791
Contact your Public Water Utility for public drinking water regulations and monitoring results.