Lead can enter drinking water when plumbing materials containing lead corrode, especially if the water is highly acidic or contains a low mineral content. The most common sources of lead in drinking water are lead pipes, faucets, and fixtures. Lead service lines that connect a building or house to the water main can also be a significant source of lead in drinking water. Lead pipes are more likely to be found in older cities and homes or buildings built before 1986. Drinking water in buildings without lead service lines may still contain lead if it leaches into the water from brass or chrome-plated brass faucets and plumbing with lead solder.
In 1991, the Environmental Protection Agency (EPA) issued the Lead and Copper Rule (LCR) to control lead and copper levels in drinking water. The LCR requires public drinking water systems to monitor drinking water at customer taps. If more than 10 percent of customer taps exceed the lead or copper action levels, the water system must implement processes to control corrosion.