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EWG's Tap Water Database — 2021 UPDATE

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Perchlorate

City of Gilroy

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

 

167

Samples

0

Samples exceeding legal limit (MCL)

3

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2014ND320ND
20150.277 ppb346ND - 2.90 ppb
2016ND310ND
2017ND340ND
2018ND360ND
2019N/A00N/A

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
2014-01-155810-001-0925ND
2014-01-155810-002-0947ND
2014-01-155810-004-1045ND
2014-01-155810-006-1100ND
2014-01-155810-007-0835ND
2014-01-155810-008-0820ND
2014-01-155810-010-0855ND
2014-04-235810-001-0900ND
2014-04-235810-002-0749ND
2014-04-235810-004-0945ND
2014-04-235810-006-1058ND
2014-04-235810-007-1039ND
2014-04-235810-008-0819ND
2014-04-235810-010-0913ND
2014-04-235810-011-0847ND
2014-07-175810-001-0946ND
2014-07-175810-002-0802ND
2014-07-175810-004-0959ND
2014-07-175810-006-0829ND
2014-07-175810-007-1011ND
2014-07-175810-008-0845ND
2014-07-175810-009-0847ND
2014-07-175810-010-0817ND
2014-10-155810-001-0759ND
2014-10-155810-002-1050ND
2014-10-155810-004-1030ND
2014-10-155810-006-0946ND
2014-10-155810-007-0836ND
2014-10-155810-008-0852ND
2014-10-155810-009-0852ND
2014-10-155810-010-0818ND
2014-10-155810-011-1010ND
2015-01-215810-001-0822ND
2015-01-215810-002-0845ND
2015-01-215810-004-1100ND
2015-01-215810-006-1030ND
2015-01-215810-007-0925ND
2015-01-215810-008-0955ND
2015-01-215810-009-1000ND
2015-01-215810-010-0905ND
2015-01-215810-011-0805ND
2015-04-225810-001-0915ND
2015-04-225810-002-0944ND
2015-04-225810-004-1305ND
2015-04-225810-006-0845ND
2015-04-225810-007-1142ND
2015-04-225810-008-1215ND
2015-04-225810-009-1239ND
2015-04-225810-010-1110ND
2015-04-225810-011-1040ND
2015-07-201644-001-08120.880 ppb
2015-07-201644-002-0830ND
2015-07-201644-004-0845ND
2015-07-201644-006-1255ND
2015-07-201644-007-10221.50 ppb
2015-07-201644-008-10452.90 ppb
2015-07-201644-009-10470.730 ppb
2015-07-201644-010-10102.70 ppb
2015-07-201644-011-09500.710 ppb
2015-10-145810-001-1040ND
2015-10-145810-004-1302ND
2015-10-145810-006-1430ND
2015-10-145810-008-1330ND
2015-10-145810-009-1340ND
2015-10-145810-010-1316ND
2015-10-145810-011-1030ND
2016-01-205810-001-0940ND
2016-01-205810-002-0832ND
2016-01-205810-004-1000ND
2016-01-205810-006-0805ND
2016-01-205810-008-0850ND
2016-01-205810-010-0925ND
2016-01-205810-011-0910ND
2016-04-255810-001-0832ND
2016-04-255810-002-1055ND
2016-04-255810-004-0855ND
2016-04-255810-006-0905ND
2016-04-255810-008-0950ND
2016-04-255810-009-0940ND
2016-04-255810-010-1041ND
2016-04-255810-011-1005ND
2016-07-205810-001-0915ND
2016-07-205810-002-0945ND
2016-07-205810-004-0930ND
2016-07-205810-006-1019ND
2016-07-205810-008-0954ND
2016-07-205810-009-0956ND
2016-07-205810-011-1035ND
2016-07-215810-010-1415ND
2016-10-135810-001-0750ND
2016-10-135810-002-0820ND
2016-10-135810-004-1010ND
2016-10-135810-006-0845ND
2016-10-135810-008-1100ND
2016-10-135810-009-1055ND
2016-10-135810-010-1025ND
2016-10-135810-011-0835ND
2017-01-185810-001-0855ND
2017-01-185810-002-0835ND
2017-01-185810-004-0805ND
2017-01-185810-006-1122ND
2017-01-185810-008-1105ND
2017-01-185810-009-1111ND
2017-01-185810-010-0955ND
2017-01-185810-011-0933ND
2017-04-135810-001-0935ND
2017-04-135810-002-0830ND
2017-04-135810-006-0915ND
2017-04-135810-008-1025ND
2017-04-135810-009-1035ND
2017-04-135810-010-1015ND
2017-04-135810-011-0800ND
2017-06-135810-004-0817ND
2017-06-135810-007-0945ND
2017-07-175810-001-1130ND
2017-07-175810-002-1250ND
2017-07-175810-007-1050ND
2017-07-175810-010-1115ND
2017-07-175810-011-1030ND
2017-07-185810-004-1125ND
2017-07-185810-006-1106ND
2017-07-185810-008-1112ND
2017-07-185810-009-1116ND
2017-10-055810-001-0805ND
2017-10-055810-004-1020ND
2017-10-055810-006-0930ND
2017-10-055810-007-0845ND
2017-10-055810-008-1000ND
2017-10-055810-009-1005ND
2017-10-055810-010-0825ND
2017-10-055810-011-0750ND
2018-01-175810-001-0835ND
2018-01-175810-004-0750ND
2018-01-175810-006-0945ND
2018-01-175810-007-1005ND
2018-01-175810-008-1035ND
2018-01-175810-009-1045ND
2018-01-175810-010-0815ND
2018-01-175810-011-0910ND
2018-02-285810-002-1320ND
2018-04-091610-001-0955ND
2018-04-091610-004-1042ND
2018-04-091610-006-0757ND
2018-04-091610-007-0837ND
2018-04-091610-008-0858ND
2018-04-091610-009-0905ND
2018-04-091610-010-0936ND
2018-04-091610-011-1018ND
2018-05-241610-002-0747ND
2018-07-091610-001-0907ND
2018-07-091610-002-0929ND
2018-07-091610-004-0947ND
2018-07-091610-006-0758ND
2018-07-091610-007-0849ND
2018-07-091610-008-0825ND
2018-07-091610-009-0830ND
2018-07-091610-010-1039ND
2018-07-091610-011-1010ND
2018-10-081610-001-0855ND
2018-10-081610-002-0911ND
2018-10-081610-004-0930ND
2018-10-081610-006-1059ND
2018-10-081610-007-0757ND
2018-10-081610-008-1028ND
2018-10-081610-009-1031ND
2018-10-081610-010-0822ND
2018-10-081610-011-1008ND