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EWG's Tap Water Database — 2021 UPDATE

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Perchlorate

West San Martin Water Works Inc.

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

 

151

Samples

0

Samples exceeding legal limit (MCL)

70

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20141.74 ppb4019ND - 5.90 ppb
20151.00 ppb2710ND - 5.00 ppb
20161.26 ppb4021ND - 4.60 ppb
20171.81 ppb1811ND - 4.50 ppb
20180.879 ppb2011ND - 2.50 ppb
20191.55 ppb63ND - 4.80 ppb

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
2014-01-092496-004-08154.60 ppb
2014-01-092496-006-0813ND
2014-01-092496-007-08142.60 ppb
2014-02-055810-004-1000ND
2014-02-122496-004-1003ND
2014-02-122496-006-1000ND
2014-02-122496-007-10012.90 ppb
2014-03-072496-004-08322.30 ppb
2014-03-072496-006-0830ND
2014-03-072496-007-08312.00 ppb
2014-04-082496-004-13332.30 ppb
2014-04-082496-006-1330ND
2014-04-082496-007-13313.10 ppb
2014-05-092496-004-12355.00 ppb
2014-05-092496-006-1232ND
2014-05-092496-007-12333.20 ppb
2014-05-135810-002-1305ND
2014-05-135810-004-13154.50 ppb
2014-06-032496-004-0842ND
2014-06-032496-006-0840ND
2014-06-032496-007-08413.20 ppb
2014-07-152496-004-12222.40 ppb
2014-07-152496-006-1220ND
2014-07-152496-007-12213.70 ppb
2014-08-112496-004-10245.90 ppb
2014-08-112496-006-1021ND
2014-08-112496-007-10224.20 ppb
2014-08-222496-007-0850ND
2014-09-052496-004-08153.60 ppb
2014-09-052496-006-0813ND
2014-09-052496-007-0814ND
2014-10-022496-004-09185.60 ppb
2014-10-022496-006-0916ND
2014-10-022496-007-0917ND
2014-11-142496-004-12074.10 ppb
2014-11-142496-006-1204ND
2014-11-142496-007-1205ND
2014-12-052496-004-09064.20 ppb
2014-12-052496-006-0903ND
2014-12-052496-007-0904ND
2015-01-072496-004-08374.10 ppb
2015-01-072496-006-0834ND
2015-01-072496-007-0835ND
2015-02-092496-004-09515.00 ppb
2015-02-092496-006-0947ND
2015-02-092496-007-0949ND
2015-03-032496-004-13052.60 ppb
2015-03-032496-006-1302ND
2015-03-032496-007-1304ND
2015-04-132496-004-11163.60 ppb
2015-04-132496-006-1114ND
2015-04-132496-007-1115ND
2015-04-285810-002-1310ND
2015-05-182496-004-09222.30 ppb
2015-05-182496-006-0919ND
2015-05-182496-007-0920ND
2015-06-032496-004-13332.40 ppb
2015-06-032496-006-1330ND
2015-06-032496-007-13320.790 ppb
2015-07-092496-004-14221.80 ppb
2015-07-092496-006-1420ND
2015-07-092496-007-1421ND
2015-07-295810-002-1435ND
2015-11-185810-002-1045ND
2015-12-182496-004-12033.30 ppb
2015-12-182496-006-1202ND
2015-12-182496-007-12041.20 ppb
2016-01-202496-004-10073.00 ppb
2016-01-202496-006-1004ND
2016-01-202496-007-1005ND
2016-02-035810-002-1005ND
2016-02-052496-004-13072.20 ppb
2016-02-052496-006-1304ND
2016-02-052496-007-1305ND
2016-03-102496-004-12363.00 ppb
2016-03-102496-006-1234ND
2016-03-102496-007-12351.30 ppb
2016-04-142496-004-13002.40 ppb
2016-04-142496-006-1258ND
2016-04-142496-007-12591.10 ppb
2016-05-172496-004-12054.00 ppb
2016-05-172496-006-1202ND
2016-05-172496-007-12030.820 ppb
2016-06-032496-004-09343.70 ppb
2016-06-032496-006-0931ND
2016-06-032496-007-09320.990 ppb
2016-07-082496-004-10063.80 ppb
2016-07-082496-006-1004ND
2016-07-082496-007-10051.30 ppb
2016-08-032496-004-10362.10 ppb
2016-08-032496-006-1033ND
2016-08-032496-007-10341.40 ppb
2016-09-122496-004-10374.60 ppb
2016-09-122496-006-1035ND
2016-09-122496-007-1036ND
2016-09-215810-002-1120ND
2016-09-215810-004-1140ND
2016-10-132496-004-11072.00 ppb
2016-10-132496-006-1104ND
2016-10-132496-007-11051.80 ppb
2016-11-142496-004-12353.40 ppb
2016-11-142496-006-1232ND
2016-11-142496-007-12341.90 ppb
2016-12-072496-004-11593.60 ppb
2016-12-072496-006-1157ND
2016-12-072496-007-11582.10 ppb
2016-12-195810-002-1345ND
2017-04-055810-002-1125ND
2017-05-252496-004-09343.60 ppb
2017-05-252496-006-09320.950 ppb
2017-05-252496-007-09333.00 ppb
2017-06-132496-004-08202.20 ppb
2017-06-132496-006-0817ND
2017-06-132496-007-08191.50 ppb
2017-07-142496-004-12354.30 ppb
2017-07-142496-006-1232ND
2017-07-142496-007-12332.20 ppb
2017-08-152496-004-10343.80 ppb
2017-08-152496-006-1032ND
2017-08-152496-007-10332.40 ppb
2017-09-265810-002-1445ND
2017-09-262496-004-11064.20 ppb
2017-10-052496-004-11094.50 ppb
2017-12-055810-002-1500ND
2017-12-125810-004-1308ND
2018-02-082706-004-15000.870 ppb
2018-02-232706-004-10061.30 ppb
2018-03-092706-004-10041.20 ppb
2018-03-212706-004-10051.30 ppb
2018-04-062706-004-1032ND
2018-04-192706-004-15301.70 ppb
2018-05-032706-004-13051.30 ppb
2018-05-182706-004-10021.60 ppb
2018-05-245810-002-1130ND
2018-06-052706-004-1231ND
2018-06-065810-002-1200ND
2018-06-212706-004-13002.40 ppb
2018-07-052706-004-1455ND
2018-07-192706-004-11312.50 ppb
2018-08-132706-004-11011.80 ppb
2018-09-055810-002-1230ND
2018-09-132706-004-1000ND
2018-11-082706-004-11001.60 ppb
2018-12-055810-002-1255ND
2018-12-112706-004-1032ND
2019-01-142706-004-12171.50 ppb
2019-03-055810-002-1405ND
2019-04-152710-004-09594.80 ppb
2019-06-245810-002-1415ND
2019-09-165810-002-1755ND
2019-10-022710-004-13333.00 ppb