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EWG's Tap Water Database — 2021 UPDATE

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Perchlorate

Golden State Water Company (GSWC) - San Dimas

Perchlorate, a component of rocket fuel, occurs both naturally and as a synthetic chemical. Ingested perchlorate interferes with thyroid function. Exposure to perchlorate during pregnancy and childhood can impair cognitive development. Read More.

According to the EPA, perchlorate likely contaminates the water of more than 16 million Americans. Perchlorate interferes with iodine uptake in the thyroid, which can result in reduced thyroid hormones and an impact on metabolism, physical development and cognitive development. Children and developing fetuses are the most at risk from perchlorate contamination.

Perchlorate is the only unregulated contaminant for which the EPA has attempted to set a federal drinking water standard since 1996. However, the agency has yet to propose a draft limit for this contaminant. Perchlorate in drinking water is regulated in Arizona, California, Massachusetts, New Jersey, New York and Texas. California set a public health goal of 1 part per billion for perchlorate in 2015.

Click here to read more about perchlorate.

MORE ABOUT THIS CONTAMINANT

 

270

Samples

0

Samples exceeding legal limit (MCL)

1

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2014ND610ND
2015ND580ND
2016ND550ND
2017ND540ND
20180.142 ppb361ND - 5.10 ppb
2019ND60ND

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 1 ppb

The EWG Health Guideline of 1 ppb for perchlorate 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. This health guideline protects against hormone disruption.

ppb = parts per billion

All test results

Date Lab ID Result
2014-01-092706-043-1320ND
2014-01-142706-043-1120ND
2014-01-212706-043-1109ND
2014-01-282706-043-1329ND
2014-02-052706-043-0848ND
2014-02-112706-043-1423ND
2014-02-192706-043-1039ND
2014-02-199588-051-0930ND
2014-02-192706-051-1030ND
2014-02-262706-043-0917ND
2014-03-052706-043-0916ND
2014-03-112706-043-1148ND
2014-03-182706-043-1416ND
2014-03-262706-043-0924ND
2014-04-012706-043-1401ND
2014-04-082706-043-1257ND
2014-04-152706-043-1339ND
2014-04-222706-043-1319ND
2014-04-292706-043-0930ND
2014-05-062706-043-0920ND
2014-05-132706-043-1238ND
2014-05-132706-051-1224ND
2014-05-149588-051-0955ND
2014-05-202706-043-0853ND
2014-05-272706-043-1039ND
2014-06-032706-043-1003ND
2014-06-102706-043-0827ND
2014-06-172706-043-0958ND
2014-06-242706-043-1143ND
2014-07-012706-043-1006ND
2014-07-082706-043-0835ND
2014-07-152706-043-1125ND
2014-07-222706-043-1017ND
2014-07-292706-043-1149ND
2014-08-052706-043-1015ND
2014-08-122706-043-1006ND
2014-08-192706-043-1141ND
2014-08-192706-051-1134ND
2014-08-262706-043-0906ND
2014-08-279588-014-0910ND
2014-08-279588-051-0940ND
2014-09-032706-043-1105ND
2014-09-092706-043-0846ND
2014-09-162706-043-1051ND
2014-09-232706-043-1013ND
2014-09-302706-043-1021ND
2014-10-072706-043-1138ND
2014-10-142706-043-1213ND
2014-10-212706-043-1228ND
2014-10-282706-043-1035ND
2014-11-042706-043-0926ND
2014-11-049588-051-0910ND
2014-11-102706-043-1318ND
2014-11-102706-051-1308ND
2014-11-182706-043-1050ND
2014-11-252706-043-1300ND
2014-12-012706-043-0910ND
2014-12-092706-043-1228ND
2014-12-162706-043-1250ND
2014-12-222706-043-1025ND
2014-12-302706-043-1150ND
2015-01-062706-043-0818ND
2015-01-132706-043-1228ND
2015-01-202706-043-1103ND
2015-01-272706-043-1428ND
2015-02-032706-043-1310ND
2015-02-102706-043-0842ND
2015-02-102706-051-0855ND
2015-02-182706-043-0925ND
2015-02-189588-051-0920ND
2015-02-242706-043-1027ND
2015-03-032706-043-1140ND
2015-03-102706-043-1113ND
2015-03-172706-043-0946ND
2015-03-242706-043-0952ND
2015-04-012706-043-0947ND
2015-04-072706-043-1010ND
2015-04-142706-043-1211ND
2015-04-212706-043-1033ND
2015-04-272706-043-1118ND
2015-05-052706-043-1138ND
2015-05-122706-043-1147ND
2015-05-122706-051-1200ND
2015-05-189588-051-0905ND
2015-05-192706-043-1225ND
2015-05-262706-043-1047ND
2015-06-022706-043-0817ND
2015-06-092706-043-1245ND
2015-06-162706-043-0949ND
2015-06-232706-043-1032ND
2015-07-012706-043-0929ND
2015-07-072706-043-1224ND
2015-07-142706-043-1220ND
2015-07-282706-043-0833ND
2015-08-042706-043-1115ND
2015-08-112706-043-0949ND
2015-08-112706-051-1007ND
2015-08-139588-051-0840ND
2015-08-182706-043-1117ND
2015-09-012706-043-1053ND
2015-09-082706-043-1029ND
2015-09-119588-014-0905ND
2015-09-162706-043-1246ND
2015-09-222706-043-1142ND
2015-09-282706-043-1003ND
2015-10-072706-043-1212ND
2015-10-132706-043-1205ND
2015-10-202706-043-1105ND
2015-10-272706-043-1212ND
2015-11-042706-043-1129ND
2015-11-102706-043-1147ND
2015-11-102706-051-1058ND
2015-11-169588-051-0835ND
2015-11-172706-043-1140ND
2015-12-012706-043-0946ND
2015-12-082706-043-0835ND
2015-12-152706-043-0937ND
2015-12-212706-043-1010ND
2015-12-282706-043-1139ND
2016-01-052706-043-0817ND
2016-01-122706-043-1230ND
2016-01-192706-043-1107ND
2016-01-272706-043-1413ND
2016-02-032706-043-1024ND
2016-02-092706-043-1227ND
2016-02-092706-051-1216ND
2016-02-169588-051-0825ND
2016-02-172706-043-1158ND
2016-02-232706-043-0818ND
2016-03-012706-043-1042ND
2016-03-082706-043-1257ND
2016-03-162706-043-0857ND
2016-03-222706-043-0914ND
2016-03-292706-043-0936ND
2016-04-052706-043-1109ND
2016-04-122706-043-1015ND
2016-04-192706-043-0954ND
2016-04-262706-043-0902ND
2016-05-032706-043-1012ND
2016-05-122706-043-1118ND
2016-05-172706-043-1127ND
2016-05-242706-043-1206ND
2016-06-012706-043-1134ND
2016-06-072710-043-1400ND
2016-06-152710-043-0953ND
2016-06-212710-043-1007ND
2016-06-282710-043-1134ND
2016-07-052710-043-1233ND
2016-07-122710-043-1219ND
2016-07-192710-043-1038ND
2016-07-262710-043-1013ND
2016-08-022710-043-1326ND
2016-08-092710-043-1142ND
2016-08-159588-014-0850ND
2016-08-162710-043-1114ND
2016-08-232710-043-1022ND
2016-08-312710-043-1146ND
2016-09-062706-043-1254ND
2016-09-132706-043-1205ND
2016-09-202706-043-1029ND
2016-09-272706-043-0921ND
2016-10-042706-043-0950ND
2016-10-112706-043-1301ND
2016-10-182706-043-1107ND
2016-10-252706-043-0936ND
2016-11-012706-043-0941ND
2016-11-082706-043-1233ND
2016-11-152706-043-1007ND
2016-11-212706-043-1019ND
2016-11-292706-043-0916ND
2016-12-062706-043-1351ND
2016-12-132706-043-1212ND
2016-12-202706-043-1011ND
2016-12-272706-043-1111ND
2017-01-039590-043-0911ND
2017-01-059588-051-0800ND
2017-01-109590-043-1137ND
2017-01-179590-043-1104ND
2017-01-249590-043-0804ND
2017-02-019590-043-1019ND
2017-02-079590-043-0940ND
2017-02-149590-043-1333ND
2017-02-149590-051-1346ND
2017-03-079590-043-1342ND
2017-03-139590-043-1412ND
2017-03-219590-043-1343ND
2017-03-319590-043-0847ND
2017-04-049590-043-1453ND
2017-04-119590-043-1345ND
2017-04-189590-043-1111ND
2017-04-259590-043-0956ND
2017-05-029590-043-0830ND
2017-05-099590-043-1300ND
2017-05-099590-051-1309ND
2017-05-159588-051-0855ND
2017-05-169590-043-1257ND
2017-05-239590-043-1054ND
2017-05-309590-043-1335ND
2017-07-039590-043-1405ND
2017-07-119590-043-1230ND
2017-07-189590-043-1329ND
2017-07-259590-043-1045ND
2017-08-019590-043-0832ND
2017-08-089590-043-1115ND
2017-08-099588-014-0755ND
2017-08-099588-051-0740ND
2017-08-159590-043-0910ND
2017-08-229590-043-1116ND
2017-08-299590-043-0902ND
2017-09-069590-043-1015ND
2017-09-129590-043-1241ND
2017-09-199590-043-0833ND
2017-09-269590-043-0952ND
2017-10-039590-043-0853ND
2017-10-119590-043-0906ND
2017-10-179590-043-1432ND
2017-10-249590-043-1102ND
2017-10-309590-043-0935ND
2017-11-079590-043-1106ND
2017-11-149590-043-1217ND
2017-11-149590-051-0840ND
2017-11-219590-043-0915ND
2017-11-229588-051-0840ND
2017-11-289590-043-0931ND
2017-12-059590-043-0844ND
2017-12-129590-043-1052ND
2017-12-199590-043-0853ND
2017-12-279590-043-1030ND
2018-01-029590-043-1010ND
2018-01-109590-043-1327ND
2018-01-169590-043-0909ND
2018-01-239590-043-1324ND
2018-01-299590-043-0953ND
2018-02-059590-043-0958ND
2018-02-129590-043-1014ND
2018-02-129590-051-1052ND
2018-02-159588-051-10455.10 ppb
2018-02-209590-043-0950ND
2018-02-269590-043-0915ND
2018-03-059590-043-0929ND
2018-03-139590-043-1123ND
2018-03-209590-043-0948ND
2018-03-279590-043-0931ND
2018-04-039590-043-1311ND
2018-04-109590-043-1337ND
2018-04-179590-043-0942ND
2018-05-019590-043-0921ND
2018-05-089590-043-1035ND
2018-05-159590-043-1039ND
2018-05-169588-051-0840ND
2018-05-229590-043-1108ND
2018-05-299590-043-1021ND
2018-06-059590-043-1322ND
2018-06-129590-043-0915ND
2018-06-199590-043-0906ND
2018-06-279590-043-1105ND
2018-07-039590-043-0830ND
2018-07-109590-043-0916ND
2018-07-179590-043-1215ND
2018-08-209588-014-0925ND
2018-08-209588-051-0840ND
2018-09-119590-051-1208ND
2018-11-149590-051-1100ND
2018-11-289588-051-0835ND
2019-02-119588-051-0835ND
2019-05-149590-051-0912ND
2019-05-229588-051-0750ND
2019-09-259588-014-0815ND
2019-12-139590-051-1405ND
2019-12-309588-051-0940ND