These top contaminants plague hundreds of California water systems

Number of water systems failing for exceeding maximum contaminant levels

A horizontal bar chart showing arsenic as the most common contaminant affecting California water systems followed closely by Total Nitrate and 1,2,3-Trichloropropane. Combined Uranium and Total Haloacetic Acids are the fourth and fifth most common respectively.
This analysis includes water systems that serve at least 25 residential customers or serve at least 15 service connections used by residential customers, water systems that serve schools and daycare facilities, and wholesale water suppliers that distribute water through at least one receiving system.
Chart: Natasha Uzcátegui-Liggett, CalMattersSource: CalMatters analysis of State Water Resources Control Board data (downloaded Sept. 9, 2024)Get the dataCreated with Datawrapper