Public drinking water systems in California violated state and federal regulations more than 4,700 times in 2016. This database contains every violation from that year. Most of the violations occurred at small systems serving fewer than 300 people, but you might consume their water even if the district doesn’t serve your home. Many of the smallest systems serve non-residential users at schools, workplaces, campgrounds, parks or ski resorts. The violations are tracked by the California State Water Resources Control Board.