How to Interpret a Water Analysis

The Environmental Protection Agency (EPA) monitors public drinking water systems to check for contaminants and to ensure treatment processes are protecting human health. Drinking water must meet health-based and aesthetic (e.g., odor and color) standards. The EPA prescribes specific water sampling procedures, analytical methods, and reporting requirements. Public water authorities follow these guidelines and produce water analysis reports.

Things You'll Need

• Water Analysis Report

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Instructions

Water Analysis Reporting

• 1

  Generally, water analysis reports display analytic results by sample location and date against maximum containment levels (MCLs) and maximum containment level goals (MCLGs) for the following possible contaminants: microorganisms, disinfectants, disinfection byproducts, inorganic chemicals, organic chemicals, and radionuclides. An MCL is the maximum permissible level of a contaminant in drinking water that is delivered to any user of a public water system. An MCLG is the maximum level of a contaminant in drinking water at which no known or anticipated adverse effects on human health occurs. It is a more stringent but non-enforceable standard.

• 2

  For example, the MCLG for dioxin, an organic chemical, is zero; the MCL is 0.00000003. The EPA has determined that dioxin at levels higher than the MCL causes reproductive difficulties and increased risk of cancer. Dioxin can get into water systems through waste combustion and incineration emissions, as well as directly from chemical factory discharges.

• 3

  A complete water analysis report includes information about the sources of contamination for all suspected contaminants. Other pertinent information includes pH, conductivity, total hardness, alkalinity, and total dissolved solids. Authorities should flag contaminants that exceed EPA standards in their reports and discuss the treatment processes they intend to implement.

• 4

  Regular analysis of public water systems helps ensure public safety. Your local water authority should post reports on its website. Also, bottled water distributors should be able to provide you with the same type of analysis report because they fall under the same EPA requirements. It is interesting to look over the reports and see what you are actually ingesting. You pay for water analysis reports with your water bill, so you might as well take a look.