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EWG's Tap Water Database — 2021 UPDATE

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Perchlorate

California Water Service - Stockton

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

 

70

Samples

0

Samples exceeding legal limit (MCL)

0

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2014ND130ND
2015ND140ND
2016ND80ND
2017ND130ND
2018ND140ND
2019ND80ND

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
2014-02-039588-013-1029ND
2014-04-029588-015-1125ND
2014-04-289588-013-1207ND
2014-04-289588-050-1112ND
2014-05-079588-055-1215ND
2014-06-039588-132-1152ND
2014-06-039588-130-1053ND
2014-06-039588-053-1400ND
2014-06-049588-058-1018ND
2014-07-309588-029-1106ND
2014-11-189588-062-1323ND
2014-12-089588-132-1039ND
2014-12-089588-130-1416ND
2015-02-239588-054-1130ND
2015-03-119588-054-1258ND
2015-03-119588-018-1231ND
2015-04-089588-051-1225ND
2015-04-159588-050-1201ND
2015-05-209588-028-1025ND
2015-05-209588-007-1149ND
2015-06-109588-130-1130ND
2015-07-149588-056-1418ND
2015-08-161610-133-1900ND
2015-10-159588-060-1215ND
2015-11-199588-059-1038ND
2015-12-089588-130-1405ND
2015-12-099588-018-0538ND
2016-02-229588-052-0709ND
2016-02-229588-067-0908ND
2016-02-239588-061-1130ND
2016-05-109588-045-1021ND
2016-06-079588-130-1227ND
2016-10-199588-064-1155ND
2016-11-089588-063-1250ND
2016-12-069588-130-1132ND
2017-04-189588-133-1113ND
2017-04-189588-015-1340ND
2017-05-159588-055-1505ND
2017-05-249588-018-1041ND
2017-06-129588-132-1020ND
2017-06-139588-130-1250ND
2017-06-139588-053-1350ND
2017-06-139588-058-0930ND
2017-07-129588-133-1405ND
2017-08-159588-029-1252ND
2017-10-109588-133-1105ND
2017-11-089588-062-1446ND
2017-12-069588-130-1456ND
2018-01-109588-133-1328ND
2018-02-219588-050-1230ND
2018-04-119588-051-1325ND
2018-04-119588-133-1035ND
2018-05-019588-007-1240ND
2018-05-019588-054-1325ND
2018-06-149588-130-1424ND
2018-06-149588-060-1509ND
2018-06-149588-059-1503ND
2018-07-119588-133-1255ND
2018-07-119588-056-1400ND
2018-10-099588-133-1317ND
2018-10-099588-028-1200ND
2018-12-119588-130-1305ND
2019-01-109588-133-1240ND
2019-01-109588-061-1032ND
2019-02-139588-052-1245ND
2019-02-139588-067-1325ND
2019-04-159588-133-1155ND
2019-06-119588-130-1132ND
2019-07-099588-133-1410ND
2019-10-099588-133-1055ND