Current EPA Microbial and Disinfection Byproduct Regulations

Disinfection Byproduct Regulations

In December 1998, EPA established the Stage 1 Disinfectants/Disinfection Byproducts Rule that requires public water systems to use treatment measures to reduce the formation of disinfection byproducts and to meet the following specific standards:

Disinfection Byproducts	Treatment Measures
Total trihalomethanes (TTHM)	80 parts per billion (ppb)
Haloacetic acids (HAA5)	60 ppb
Bromate	10 ppb
Chlorite	1.0 parts per million (ppm)

Currently trihalomethanes are regulated at a maximum allowable annual average level of 100 parts per billion for water systems serving over 10,000 people under the Total Trihalomethane Rule finalized by EPA in 1979. The Stage 1 Disinfectant/Disinfection Byproduct Rule standards will become effective for trihalomethanes and other disinfection byproducts listed above in December 2001 for large surface water public water systems. Those standards will become effective in December 2003 for small surface water and all ground water public water systems.

Data from the ICR and research will be used to develop the Stage 2 Disinfectants/Disinfection Byproducts Rule by May 2002 to help further control disinfection byproducts.

Microbial Regulations

One of the key regulations developed and implemented by the United States Environmental Protection Agency (USEPA) to counter pathogens in drinking water is the Surface Water Treatment Rule. Among its provisions, the rule requires that a public water system, using surface water (or ground water under the direct influence of surface water) as its source, have sufficient treatment to reduce the source water concentration of Giardia and viruses by at least 99.9% and 99.99%, respectively. The Surface Water Treatment Rule specifies treatment criteria to assure that these performance requirements are met; they include turbidity limits, disinfectant residual, and disinfectant contact time conditions.

The Interim Enhanced Surface Water Treatment Rule was established in December 1998 to control Cryptosporidium, and to maintain control of pathogens while systems lower disinfection byproduct levels to comply with the Stage 1 Disinfectants/Disinfection Byproducts Rule. EPA established a Maximum Contaminant Level Goal (MCLG) of zero for all public water systems and a 99% removal requirement for Cryptosporidium in filtered public water systems that serve at least 10,000 people. The new rule will tighten turbidity standards by December 2001. Turbidity is an indicator of the physical removal of particulates, including pathogens.

EPA is also planning to develop other rules to further control pathogens. EPA will be promulgating a Long Term 1 Enhanced Surface Water Treatment Rule, for systems serving fewer than 10,000 people, in November 2000 to improve physical removal of Cryptosporidium, and to maintain control of pathogens while systems comply with Stage 1 Disinfectants/Disinfection Byproducts Rule . Data from the ICR and research will be used to develop the Long Term 2 Enhanced Surface Water Treatment Rule by 2002 to improve control of microbial pathogen risk, and for simultaneous compliance with the Stage 2 Disinfectants/Disinfection Byproducts Rule.

Data from the ICR and research will be used to develop the Long Term 2 Enhanced Surface Water Treatment Rule, expected in May 2002 to improve control of microbial pathogen risk, and for simultaneous compliance with the Stage 2 Disinfectants/Disinfection Byproducts Rule.

Drinking Water Priority Rulemaking: Microbial and Disinfection Byproduct Rules

Current EPA Microbial and Disinfection Byproduct Regulations

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