Lead and Copper Rule
In 1992, the United States Environmental Protection Agency (EPA) adopted the Lead and Copper Rule for drinking water. Lead or copper in tap water is primarily due to corrosion of plumbing system components within buildings. Plumbing components include copper pipes, lead-based solder used to join segments of copper pipe, and faucets made from brass that contains lead.

The rule sets action levels for lead and copper in standing samples collected from faucets with the highest risk for elevated lead and copper levels. The action level for lead is 15 micrograms per liter of water. This compares to 1/10 of one teaspoon of sugar in 10,000 gallons of water. The copper action level is 1.3 milligrams per liter of water. If the monitoring results for a public water system exceed the action level for lead, the water system must conduct a public information campaign, and may be required to treat source water to control corrosion.

The Chicago Water Department, the agency that treats the water provided by the DuPage Water Commission, is adding blended phosphates for corrosion control to comply with the Lead and Copper Rule. The function of the blended phosphates is to provide a coating on the interior of the watermains, house services and interior plumbing to prevent lead and copper leaching.