Action Level

The level of lead or copper which, if exceeded in over 10% of the homes tested, triggers treatment or other requirements that a water system must follow.

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Acute Health Effect

An immediate (i.e., within hours or days) adverse health effect that may result from exposure to certain drinking water contaminants (e.g., pathogens).

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Aquifer

A natural underground layer, often of sand or gravel, that contains water.

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Best Available Technology

The water treatment(s) that US EPA certifies to be the most effective for removing a contaminant.

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Chronic Health Effect

The possible result of exposure over many years to a drinking water contaminant at levels above its Maximum Contaminant Level.

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Coliform

A group of related bacteria whose presence in drinking water may indicate contamination by disease-causing microorganisms.

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Community Water System

A public water system which supplies drinking water to 25 or more of the same people year-round in their residences.

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Compliance

The act of meeting all state and federal drinking water regulations.

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Contaminant

Anything found in water (including microorganisms, minerals, chemicals, radionuclides, etc.) which may be harmful to human health.

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Cryptosporidium

A microorganism commonly found in lakes and rivers which is highly resistant to disinfection. Cryptosporidium has caused several large outbreaks of gastrointestinal illness, with symptoms that include diarrhea, nausea, and/or stomach cramps. People with severely weakened immune systems are likely

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