Lead Contamination in Washington, D.C. Drinking Water

The discovery of widespread lead contamination in Washington, D.C. drinking water resulted in a Congressional investigation that damaged the scientific reputation of the Centers for Disease Control and Prevention (CDC), left thousands of children with lifelong health risks, and led to a re-evaluation of the use of chloramine in public drinking-water systems. Marc Edwards, an expert in plumbing corrosion, discovered lead levels at least 83 times higher than the accepted safe limit while performing research into premature pipe corrosion for the District of Columbia Water and Sewer Authority (WASA). He found that the decision to change from using chlorine to chloramine as a treatment chemical had caused the spike in lead levels. After the Washington Post ran a series of front-page articles about Edwards's findings, resulting in widespread public concern, the United States House of Representatives conducted an investigation. The House found that the CDC had made "scientifically indefensible" claims in a report that had indicated there was no risk from the high lead levels. The Post investigation uncovered evidence of widespread misreporting of lead levels at water agencies across the United States, leading to regulatory crackdowns and changes in Environmental Protection Agency policies.

The problem was addressed in 2004 by adding additional treatments to the water, preventing the chloramine from dissolving lead in the water mains, solder joints, and fixtures.

In 2010, the CDC reported that 15,000 homes in the Washington, D.C. area might still have water supplies with dangerous levels of lead.