EWG's Tap Water Database — 2019 UPDATE



Taunton Water Division

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.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20120.180 ppb110.180 ppb
20130.215 ppb220.210 ppb - 0.220 ppb
20140.410 ppb220.260 ppb - 0.560 ppb
20150.105 ppb220.1000 ppb - 0.110 ppb
20160.235 ppb220.220 ppb - 0.250 ppb
20170.0800 ppb110.0800 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 Result
2012-09-120.180 ppb
2013-08-080.220 ppb
2013-09-160.210 ppb
2014-05-130.560 ppb
2014-09-100.260 ppb
2015-08-310.1000 ppb
2015-08-310.110 ppb
2016-09-010.250 ppb
2016-09-010.220 ppb
2017-07-050.0800 ppb