In 1991, the U.S. EPA published the Lead and Copper Rule. This regulation sets "action levels" for lead and copper in water. Action levels are not health standards but are set to limit the amount of lead and copper in drinking water.
The current regulations are designed to inform water system consumers of wholesale problems in their water supply. The regulations place an emphasis on optimizing the chemical properties of the distributed water to reduce its corrosiveness (such as pH or alkalinity adjustments) and thereby reduce the risk of lead contamination. While these measures can be effective in a large sense, they may not be effective with respect to individual properties subject to site specific conditions that increase their risk. The City of Aurora reduces corrosion via the lime softening process utilized at the Water Treatment Plant. The corrosion control reduces the amount of lead corrosion that can occur in customer's service lines and plumbing. This is accomplished by maintaining proper levels of pH, total alkalinity, and calcium. Each of these parameters are measured four times a day, every day, to ensure proper corrosion control is constantly provided to reduce the amount of lead entering drinking water. These corrosion control measures have successfully reduced lead levels in water in the city.
The Lead and Copper Rule requires that all public drinking water systems regularly test a sample of high-risk homes for lead at the tap. If more than 10% of homes tested have lead concentrations higher than the U.S. EPA "action level" of 15 parts per billion, the city would be required to notify area residents via newspapers, radio, TV, and other means. If the lead level remains consistently above the action level, the city must take additional steps to reduce lead in water.
Aurora water customers voluntarily assist the City by collecting water samples from their taps in their homes during the proper sampling periods. The sampling locations, times, and specific collection procedures are regulated by the Illinois EPA. The Lead and Copper Rule is the only Federal drinking water regulation that requires sampling from household taps and thus, the City is accountable for results that are representative of pipes and plumbing on both public and private property. Under the Lead and Copper Rule compliance monitoring program, Aurora is currently required to collect water samples from 50 customer homes throughout the city every year. Sample sites are reviewed and approved by the Illinois EPA each sampling cycle. The City delivers sampling kits to these homes with detailed water collection instructions, and homeowners are responsible for collecting the water samples.
The City of Aurora's drinking water fully complies with the federal Lead and Copper Rule. The 90th percentile results for lead from the required sampling conducted since 2004 are shown in the chart below: