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EWG's Tap Water Database — 2021 UPDATE

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Uranium

Zone 7 Water Agency

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.

MORE ABOUT THIS CONTAMINANT

 

217

Samples

0

Samples exceeding legal limit (MCL)

93

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20140.80 pCi/L3515ND - 3.20 pCi/L
20150.19 pCi/L304ND - 2.90 pCi/L
20160.94 pCi/L3015ND - 3.30 pCi/L
20170.79 pCi/L175ND - 4.20 pCi/L
20181.11 pCi/L4925ND - 3.80 pCi/L
20191.05 pCi/L5629ND - 3.90 pCi/L

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
2014-01-065100-001-0945ND
2014-01-065100-006-11201.70 pCi/L
2014-01-065100-008-0915ND
2014-01-065100-012-12402.80 pCi/L
2014-02-035100-001-1025ND
2014-02-185100-008-0950ND
2014-03-245100-001-1000ND
2014-03-245100-008-1045ND
2014-04-075100-001-0940ND
2014-04-075100-008-1120ND
2014-05-055100-001-0930ND
2014-05-055100-008-1035ND
2014-06-095100-001-1000ND
2014-06-095100-008-1055ND
2014-06-105100-005-10003.10 pCi/L
2014-06-105100-011-10401.30 pCi/L
2014-06-115100-006-08251.40 pCi/L
2014-06-115100-013-09302.10 pCi/L
2014-06-165100-007-09101.10 pCi/L
2014-06-175100-012-11252.30 pCi/L
2014-06-195100-019-09351.00 pCi/L
2014-07-075100-001-1000ND
2014-07-075100-008-1015ND
2014-08-045100-001-0950ND
2014-08-045100-008-1035ND
2014-08-115100-005-09203.00 pCi/L
2014-08-115100-011-09401.30 pCi/L
2014-09-085100-001-0840ND
2014-09-085100-006-11501.10 pCi/L
2014-09-085100-008-1043ND
2014-09-095100-007-09301.20 pCi/L
2014-09-105100-005-08303.20 pCi/L
2014-09-105100-011-08001.40 pCi/L
2014-10-065100-001-1110ND
2014-10-065100-008-0825ND
2015-01-055100-001-0935ND
2015-01-055100-008-0945ND
2015-02-025100-008-0955ND
2015-03-025100-001-1005ND
2015-03-035100-017-0825ND
2015-03-245100-019-10051.10 pCi/L
2015-04-135100-001-0850ND
2015-04-135100-008-0840ND
2015-05-045100-001-0945ND
2015-05-045100-008-1025ND
2015-06-225100-001-1100ND
2015-06-225100-008-0845ND
2015-06-245100-019-08450.70 pCi/L
2015-06-255100-017-0955ND
2015-06-265100-005-09052.90 pCi/L
2015-06-265100-007-09301.00 pCi/L
2015-07-065100-001-0855ND
2015-07-065100-008-1036ND
2015-08-035100-001-0920ND
2015-08-035100-008-1010ND
2015-09-085100-001-0930ND
2015-09-085100-008-1030ND
2015-09-105100-017-0910ND
2015-10-055100-001-0950ND
2015-10-055100-008-0920ND
2015-11-025100-001-0927ND
2015-11-025100-008-0915ND
2015-11-025100-008-0925ND
2015-11-235100-017-1110ND
2015-12-075100-001-0930ND
2016-01-045100-001-0930ND
2016-02-015100-001-1405ND
2016-02-035100-012-10502.20 pCi/L
2016-02-095100-005-08553.30 pCi/L
2016-02-095100-011-08421.60 pCi/L
2016-03-035100-006-11001.10 pCi/L
2016-03-035100-017-0935ND
2016-03-295100-007-12451.30 pCi/L
2016-03-305100-020-1030ND
2016-04-045100-005-10443.30 pCi/L
2016-04-045100-008-0905ND
2016-04-045100-013-14253.00 pCi/L
2016-04-045100-019-11351.00 pCi/L
2016-04-065100-012-11052.20 pCi/L
2016-04-065100-020-11551.20 pCi/L
2016-05-025100-007-09001.20 pCi/L
2016-05-025100-017-0945ND
2016-05-025100-019-12251.00 pCi/L
2016-05-045100-001-0825ND
2016-05-045100-008-1200ND
2016-05-195100-020-1058ND
2016-06-025100-005-08203.20 pCi/L
2016-06-065100-001-0935ND
2016-06-065100-008-1025ND
2016-07-115100-001-0920ND
2016-07-115100-007-12201.60 pCi/L
2016-07-115100-008-1010ND
2016-07-115100-020-13171.00 pCi/L
2016-07-135100-017-1035ND
2016-07-135100-019-0920ND
2017-07-105100-007-10101.90 pCi/L
2017-07-105100-019-11351.10 pCi/L
2017-07-115100-001-0935ND
2017-07-115100-008-0955ND
2017-07-115100-017-1210ND
2017-07-125100-012-09003.30 pCi/L
2017-07-135100-013-00152.90 pCi/L
2017-07-315100-020-1040ND
2017-08-095100-001-1015ND
2017-08-095100-008-1035ND
2017-09-055100-001-0900ND
2017-09-055100-008-0947ND
2017-09-255100-005-10104.20 pCi/L
2017-11-065100-001-0915ND
2017-11-065100-008-1050ND
2017-12-045100-001-0900ND
2017-12-045100-008-0945ND
2018-02-055100-012-09053.60 pCi/L
2018-02-055100-017-0950ND
2018-02-065100-001-0958ND
2018-02-065100-005-09123.10 pCi/L
2018-02-065100-011-08552.00 pCi/L
2018-02-285100-006-09451.40 pCi/L
2018-02-285100-008-1100ND
2018-03-075100-001-1123ND
2018-03-075100-008-1010ND
2018-04-095100-001-1137ND
2018-04-095100-008-1020ND
2018-04-095100-017-1035ND
2018-04-105100-005-12403.70 pCi/L
2018-04-105100-011-12152.00 pCi/L
2018-04-105100-019-09251.60 pCi/L
2018-04-115100-006-10101.40 pCi/L
2018-04-115100-012-10403.20 pCi/L
2018-04-115100-013-09403.40 pCi/L
2018-05-075100-001-1515ND
2018-05-075100-008-1330ND
2018-06-045100-001-0920ND
2018-06-045100-008-1010ND
2018-07-095100-001-1225ND
2018-07-095100-005-13503.80 pCi/L
2018-07-095100-008-0925ND
2018-07-095100-013-09303.50 pCi/L
2018-07-095100-017-11201.00 pCi/L
2018-07-095100-019-10001.30 pCi/L
2018-07-115100-005-09001.60 pCi/L
2018-07-115100-006-09351.20 pCi/L
2018-07-115100-011-09001.60 pCi/L
2018-08-065100-001-0935ND
2018-08-065100-008-0925ND
2018-08-075100-007-08452.40 pCi/L
2018-09-105100-001-0830ND
2018-09-105100-008-0840ND
2018-09-255100-020-1314ND
2018-10-085100-001-0825ND
2018-10-085100-008-0955ND
2018-10-085100-012-11202.60 pCi/L
2018-10-085100-019-11401.50 pCi/L
2018-10-095100-017-0900ND
2018-10-105100-007-14351.90 pCi/L
2018-10-105100-020-14151.20 pCi/L
2018-12-035100-008-1010ND
2018-12-035100-020-10051.00 pCi/L
2018-12-045100-013-09202.90 pCi/L
2018-12-045100-019-10001.40 pCi/L
2018-12-175100-001-0923ND
2019-01-075100-005-12153.10 pCi/L
2019-01-075100-008-1017ND
2019-01-075100-012-11002.10 pCi/L
2019-01-075100-017-1025ND
2019-01-075100-020-1150ND
2019-01-085100-007-09101.70 pCi/L
2019-01-085100-011-10152.10 pCi/L
2019-01-085100-019-09401.50 pCi/L
2019-02-045100-008-1028ND
2019-03-045100-008-0907ND
2019-04-085100-007-11301.60 pCi/L
2019-04-085100-008-0925ND
2019-04-085100-017-0916ND
2019-04-095100-006-09201.50 pCi/L
2019-04-095100-012-09351.60 pCi/L
2019-04-095100-013-09552.40 pCi/L
2019-04-095100-019-10401.40 pCi/L
2019-05-065100-001-0850ND
2019-05-065100-008-1215ND
2019-06-035100-001-0940ND
2019-06-035100-008-0910ND
2019-07-085100-005-10153.70 pCi/L
2019-07-085100-007-09501.50 pCi/L
2019-07-085100-011-09452.10 pCi/L
2019-07-085100-013-10152.90 pCi/L
2019-07-085100-020-11301.60 pCi/L
2019-07-095100-006-11451.60 pCi/L
2019-07-095100-017-0925ND
2019-07-095100-019-10452.30 pCi/L
2019-07-105100-001-1010ND
2019-07-105100-008-1115ND
2019-08-055100-001-1105ND
2019-08-055100-008-0915ND
2019-08-055100-012-09051.60 pCi/L
2019-08-055100-020-0935ND
2019-09-095100-001-0840ND
2019-09-095100-008-1005ND
2019-10-075100-001-1325ND
2019-10-075100-005-11503.90 pCi/L
2019-10-075100-006-09001.60 pCi/L
2019-10-075100-007-08301.40 pCi/L
2019-10-075100-008-1210ND
2019-10-075100-011-10503.10 pCi/L
2019-10-075100-012-10151.60 pCi/L
2019-10-075100-013-09452.70 pCi/L
2019-10-075100-020-09201.10 pCi/L
2019-10-085100-017-0830ND
2019-10-085100-019-10152.40 pCi/L
2019-11-045100-001-0855ND
2019-11-045100-008-1030ND
2019-12-025100-008-1006ND
2019-12-025100-020-08501.00 pCi/L
2019-12-035100-017-1155ND
2019-12-035100-019-13402.10 pCi/L
2019-12-105100-017-1100ND
2019-12-105100-019-09421.80 pCi/L