Water Education - Water and Health

Standards for Safe Drinking Water

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It is known that no one method of filtering or purifying water is going to eliminate 100% of elements from our drinking water. That said, water can be safe and acceptable, within reason. There are guidelines, set by the U.S. EPA, which measure water standards to make sure our water is safe.

"Acceptable" contamination levels of water are measured by two standards: maximum contaminant level (MCL) and maximum contaminant level goal (MCLG). For the list of individual contaminant standards, please click here.

The goal indicates the level of contaminants at or below which is considered safe for human consumption. However, given the size of most water systems, today's technological limitations, and the costs involved with water purification, it is impossible to provide the masses with water at or below goal level for all contaminants.


Because of these difficulties, the MCL standard was created as a compromise between public safety and feasibility, dictating levels that must be met before water is distributed to the public. This level is usually within 5% of acceptable contaminant range.

Post-Filtration Contaminants

Turbidity is a measure of the cloudiness of water, and an indication of filtration effectiveness. Cloudy water is a sign of the presence of microorganisms that can cause gastrointestinal illness. Although controlled at the original filtration source, soil runoff and other factors can affect turbidity levels by the time water reaches a faucet.

The pipelines that transport water from its original purification source to homes and businesses can affect certain contaminant levels. These include:

  • vinyl chloride, known to increase the risk of cancer (goal level is 0; actual level is 0.02%);
  • lead, which causes high blood pressure and kidney disease in adults and developmental delays in children (goal level is 0; actual level is 0.015 mg/L);
  • copper, which contributes to gastrointestinal disease in the short-term and liver/kidney damage in the long-term (goal/actual level of 1.3 mg/L);
  • cadmium, known to cause kidney damage (goal/actual level of 0.005 mg/L).
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