As discussed in a prior post, one of the most important advances in public water supply was implementation of treatment with chlorination. Adopted by utilities in early 20th century, disinfection of water ended typhoid fever as a serious concern in this country. (See "Safe Drinking Water: A Beginning", Water Lawg, January 12, 2010)
So, I was surprised to learn recently that some 60 communities in Wisconsin allegedly do not disinfect their public water supply, whether by chlorination or by any alternative methodology. Apparently, the state legislature repealed any disinfection requirement, asserting that it was an unnecessary financial and administrative burden.
Pursuant to the federal Safe Drinking Water Act, USEPA has adopted Maximum Contaminant Levels (MCLs) and Maximum Contaminant Level Goals (MCLGs) for several categories of microorganisms. Public Water Supplies must comply with MCLs for all water delivered to users. USEPA states that "there is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants." (See water.epa.gov/drink/contaminants/index.cfm)
In apparent contrast to Wisconsin, Illinois regulations require disinfection treatment with chlorine or other protocol approved by the Illinois Environmental Protection Agency. Illinois also requires chlorination before finished water enters the distribution system sufficient to maintain a specified chlorine residual in the distribution mains.
Bacteria and viruses can enter a public water supply from either surface water supplies or ground water wells. They also can enter through defects in mains or even as a result of unprotected back flows. Regardless whether disinfection is a regulatory requirement, a public water supply still must comply with MCLs for bacteria, viruses and other contaminants. A utility electing to not provide disinfection treatment may also want assure that it has adequate insurance coverage.
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