In 1974, Congress passed the Safe Drinking Water Act. This law requires EPA to determine the level of contaminants in drinking water at which no adverse health effects are likely to occur. These non-enforceable health goals, based solely on possible health risks and exposure over a lifetime with an adequate margin of safety, are called maximum contaminant level goals (MCLG). Contaminants are any physical, chemical, biological or radiological substances or matter in water.
The MCLG for epichlorohydrin is zero. EPA has set this level of protection based on the best available science to prevent potential health problems.
For most contaminants, EPA sets an enforceable regulation called a maximum contaminant level (MCL) based on the MCLG. MCLs are set as close to the MCLGs as possible, considering cost, benefits and the ability of public water systems to detect and remove contaminants using suitable treatment technologies. When there is no reliable method that is economically and technically feasible to measure a contaminant at particularly low concentrations, a treatment technique is set rather than an MCL. A treatment technique is an enforceable procedure or level of technological performance which water systems must follow to ensure control of a contaminant.
EPA has regulated epichlorohydrin using a treatment technique requirement in lieu of an MCL because of the absence of standardized analytical method for its measurement in water.
The Phase II rule, which includes the regulation for epichlorohydrin, limits the amount of epichlorohydrin in the polymeric coagulant aids to 0.01 percent by weight and the dosage of polymeric coagulant aid which can be added to drinking water to remove particulates, to 20 parts per million (ppm). Under this regulation, each water system is required to certify annually, in writing, to the Primacy authority that the coagulant aid's epichlorohydrin content and application dose do not exceed the levels specified in the rule. A water system may use third-party or manufacturer’s certification in lieu of testing for epichlorohydrin level in coagulant aids.
The Phase II rule became effective in 1992. The Safe Drinking Water Act requires EPA to periodically review the national primary drinking water regulation for each contaminant and revise the regulation, if appropriate. EPA reviewed epichlorohydrin during the first Six Year Review and determined that the zero mg/L and the treatment technique requirement for epichlorohydrin were are still protective of human health.
States may set a more stringent regulatory requirement for epichlorohydrin in drinking water than EPA.