Lead contamination in Washington, D.C., drinking water

While performing research into premature pipe corrosion for the District of Columbia Water and Sewer Authority (WASA) in 2001, Marc Edwards, an expert in plumbing corrosion, discovered lead levels in the drinking water of Washington, D.C., at least 83 times higher than the accepted safe limit. He found that the decision to change from chlorine to chloramine as a treatment chemical had caused the spike in lead levels.

Source: Wikipedia — Lead contamination in Washington, D.C., drinking water (CC BY-SA 4.0)