Home source 1,741 districts violated drinking water rules in 2016. Did you drink their...

1,741 districts violated drinking water rules in 2016. Did you drink their water?

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.

The most serious violations involve the “total coliform rule.” The presence of fecal coliform is associated with contamination by sewage or animal waste and can result in immediate health impacts such as diarrhea, nausea and other symptoms. Other types of water contamination might take months or years of exposure to cause harm. Violations are also assessed when a water system doesn’t issue legally required public notifications.


Search the database by entering the name of a water district in the search box, or by selecting a county from the drop-down menu.

What it all means

The violations fall into three main categories:

▪  Monitoring and Reporting (MR): The water system did not test its water as required, or failed to report results in a timely fashion to regulators or the public.

▪  Maximum Containment Level (MCL): Test results showed that containment levels exceeded safety limits.

▪  Treatment Technique (TT): The water system did not follow required techniques to reduce the risk from contaminants for which an MCL is infeasible for impractical.

Public drinking water is tested for these contaminants (water systems that serve people for only part of the year – such as campgrounds, parks and motels – don’t have to test for contaminants that require long-term exposure to pose health risks):

Inorganic contaminants: There are 18 of these contaminants, six of which were found in California drinking water in 2016. Nirate and nitrite can mean sewage contamination. High levels can cause serious illness, and death in rare cases for infants. There are 335 related violations in the database. The other contaminants found in 2016 were arsenic (cancer, skin damage, circulatory problems), unsafe levels of fluoride (bone disease), mercury (impairs speech, hearing, coordination and mental function) and cadmium (kidney damage).

Synthetic organic contaminants: The only contaminant in this class found in state drinking water in 2016 was dibromochloropropane, a soil fumigant banned in 1978. It is still found in groundwater in some areas, and long-term exposure can cause reproductive difficulties and increased cancer risk.

Volatile organic contaminants: Of the 27 VOCs water systems must monitor, only trichloroethylene was found in 2016. It is a discharge from metal degreasing sites and factories that can cause liver problems and increased cancer risk after long-term exposure.

Radionuclides: Water systems monitor for beta particles and photon radioactivity in drinking water. Combined uranium, the only violation found in 2016, can come from erosion of natural deposits. Long-term exposure can lead to kidney problems and increased cancer risk.

Total coliform rule: All water systems must monitor for coliform bacteria, which can indicate contamination from sewage or animal waste that can have immediate health risks – including diarrhea, cramps and nausea.

Disinfectants and their byproducts: To protect against disease-causing microbes, water systems add chemical disinfectants to drinking water. These disinfectants can react with naturally occurring organic matter and produce byproducts that pose long-term health risks. Trihalomethanes are are byproduct that can cause liver, kidney and nervous system problems over time. Haloacetic acids can increase cancer risk.

Surface water treatment rules: These rules establish standards to remove microbiological contaminants such as Giardia lamblia, Cryptosporidium parvum, Legionella bacteria and viruses.

Groundwater rule: Establishes standards for groundwater systems that are vulnerable to fecal contamination.

Lead and copper: Lead is generally present in water due to corrosion of water lines or household plumbing. It can cause serious health effects, including developmental delays in children and kidney problems in adults. When lead and copper are found in drinking water, water systems must take action to control corrosion and educate the public to reduce its exposure.

Learn more at the Sacramento Bee



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