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Pennsylvania Safe Drinking Water Regulations

Pennsylvania, like all states, regulates drinking water supplies to insure water from the tap is safe to drink. The Department of Environmental Protection (DEP) monitors public water supply treatment, operations and corrective actions so that water quality meets maximum contaminant levels (MCLs), the permissible level of contaminant in water delivered to the tap, or point of entry for bottled water, vended, retail or bulk water systems. MCLs are set by the federal government through the Clean Water Act (CWA) at levels protective of public health and adopted by the states, who are responsible for enforcement.

  1. MCLs: 40 CFR 141

    • MCLs have been developed for micro-organisms (disease causing biological materials), disinfectants (chlorine), inorganic chemicals (metals), organic chemicals (for example, gasoline by-products) and radionuclides (radioactive compounds). MCLs have been established based upon risks to the general, otherwise healthy, public. The EPA has reviewed health studies for problematic contaminants and established the maximum level at which "no known or anticipated adverse effect on health of persons would occur" with an adequate margin of safety.

    Treatment Technologies: PA Code 109.201

    • The Pennsylvania DEP mandates that public water systems must comply with MCLs through implementation of treatment technologies, for example, filtration and disinfection. Filtration systems must filter water through granular activated carbon or membrane technology to remove substances. Disinfection, using chlorine or other substances, removes disease-causing entities, for example, giardia, a parasite that lives in the intestinal tract of humans and animals and is transported via waste water pipes and seepage into groundwater.

    Variances: PA Code 109.901

    • A variance excuses certain public water suppliers from meeting quality standards.The DEP may grant one or more variances from meeting MCLs if special conditions exist. If best available treatment technologies and methods are installed and there is no "reasonably available" alternative source of water, a variance may be granted. Similarly, variances are granted when the characteristics of the raw water supply cannot meet an MCL and there is "no unreasonable" risk to the public. MCLs for total coliform are never eligible for variances, and neither are certain treatment technologies, such as treatments that protect the public from pathogenic bacteria, viruses and protozoan cysts; treatments that control pipe erosion to prevent lead and copper from entering the water supply; monitoring requirements for cryptosporidium (a parasite resistant to chlorine disinfection and so must be monitored closely to identity its appearance in water systems); and disinfectants for groundwater systems at the point of entry.

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