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EWG's Tap Water Database — 2021 UPDATE

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Uranium

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Uranium is a known human carcinogen. The federal legal limit for uranium is set at 30 micrograms per liter (corresponding to parts per billion), but utilities can also report uranium in picocuries per liter (pCi/L), which is a measure of radioactivity in water. EWG translated all uranium results to pCi/L using a conversion factor developed by the EPA. With this conversion approach, the limit of 30 ppb corresponds to 20 pCi/L. Drinking water with this much uranium would cause more than 4.6 cancer cases in a population of 100,000. California set a public health goal for uranium of 0.43 pCi/L. Read More.

Multiple forms of uranium can be detected in water, including uranium-234, uranium-235 and uranium-238. Uranium-234 is the most toxic form of uranium for human health.

 

15

Samples

0

Samples exceeding legal limit (MCL)

0

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2014N/A00N/A
2015ND10ND
2016ND40ND
2017ND40ND
2018ND40ND
2019ND20ND

pCi/L = picocuries per liter

State and national drinking water standards and health guidelines

EWG Health Guideline 0.43 pCi/L

The EWG Health Guideline of 0.43 pCi/L for uranium was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. Three most common uranium isotopes are U-234, U-235 and U-238. All isotopes of uranium are radioactive, and the total radioactivity depends on the ratio of isotopes. This health guideline protects against cancer.

EPA Maximum Contaminant
Level (MCL) 20 pCi/L

pCi/L = picocuries per liter

All test results

Date Lab ID Result
2015-02-1241743ND
2016-02-0230172223001ND
2016-04-1130179350001ND
2016-08-0230191875001ND
2016-10-1230198977001ND
2017-02-1430210763001ND
2017-04-2530217083001ND
2017-09-1130229706001ND
2017-10-1730233281001ND
2018-02-1330243434001ND
2018-04-2430250641001ND
2018-07-2430260178001ND
2018-12-1930274993001ND
2019-04-1730289940001ND
2019-09-05011911369-0001ND