Maximum Contaminant Level Goal (MCLG): The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety.

Action Level: The concentration of a contaminant which, if exceeded, triggers treatment or other requirements which a water system must follow.

mg/L: One milligram per liter (mg/L) is equal to one part per million (ppm), which is approximately the same as 1 second in 11.5 days.

µg/L: One microgram per liter (µg/L) is equal to one part per billion (ppb), which is approximately the same as 1 second in 31.7 years.

Lead Exposure MCLG (µg/L) Action Level (µg/L)
0 15


Copper Exposure MCLG (mg/L) Action Level (mg/L)
1.3 1.3

Health Effects of Lead Exposure above 15 µg/L

The health effects of lead are most severe for infants and children. For infants and children, exposure to high levels of lead in drinking water can result in delays in physical or mental development. For adults, it can result in kidney problems or high blood pressure. Although the main sources of exposure to lead are ingesting paint chips and inhaling dust, EPA estimates that 10 to 20 percent of human exposure to lead may come from lead in drinking water. Infants who consume mostly mixed formula can receive 40 to 60 percent of their exposure to lead from drinking water.

Health Effects of Copper Exposure above 1.3 mg/L

Copper is an essential nutrient, but some people who drink water containing copper in excess of the action level over a relatively short amount of time could experience gastrointestinal distress. Some people who drink water containing copper in excess of the action level over many years could suffer liver or kidney damage. People with Wilson’s Disease should consult their personal doctor.

Steps Customers Can Take to Reduce Exposure to Lead & Copper in Drinking Water (from US EPA)

Flush your pipes before drinking, and only use cold water for consumption. The more time water has been sitting in your home’s pipes, the more lead it may contain. Anytime the water in a particular faucet has not been used for six hours or longer, “flush” your cold-water pipes by running the water until it becomes as cold as it will get. This could take as little as five to thirty seconds if there has been recent heavy water use such as showering or toilet flushing. Otherwise, it could take two minutes or longer. Your water utility will inform you if longer flushing times are needed to respond to local conditions.

Use only water from the cold-water tap for drinking, cooking, and especially for making baby formula. Hot water is likely to contain higher levels of lead. The two actions recommended above are very important to the health of your family. They will probably be effective in reducing lead levels because most of the lead in household water usually comes from the plumbing in your house, not from the local water supply.

More information on lead in drinking water is available on the US EPA web site at