EWG's Tap Water Database — 2019 UPDATE



Galveston County WCID 1

Atrazine is a herbicide commonly detected in drinking water that comes from cornfield and other agricultural runoff. It is a hormone disrupter that harms the male and female reproductive systems of people and wildlife. Read More.

Federal laws allow up to 3 parts per billion of atrazine in treated tap water. Water suppliers average atrazine measurements collected over a year, which means that the reported values underestimate intense spikes of elevated exposures during the periods in late spring and early summer when atrazine is applied in large amounts on farm fields.

Human epidemiological studies suggest that federal standards for atrazine are insufficient to protect public health. In 1999 the California Office of Environmental Health Hazard Assessment set a public health goal of 0.15 parts per billion for atrazine in drinking water, based on a study finding increased rates of breast cancer in rats exposed to the chemical. California’s legal maximum for atrazine in tap water is 1 ppb.

Click here to read more about atrazine.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20120.0333 ppb31ND - 0.1000 ppb
20130.150 ppb330.140 ppb - 0.160 ppb
20140.133 ppb330.130 ppb - 0.140 ppb
20150.0800 ppb32ND - 0.120 ppb
20160.0400 ppb31ND - 0.120 ppb
20170.0567 ppb31ND - 0.170 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.1 ppb

The EWG Health Guideline of 0.1 ppb for atrazine was defined by EWG based on epidemiological studies of human exposure to atrazine in drinking water.. This health guideline protects against harm to the developing fetus, harm to the reproductive system and hormone disruption.

EPA Maximum Contaminant
Level (MCL) 3 ppb

The legal limit for atrazine, established in 1991, was based on a toxicity study in laboratory animals conducted in the 1980s. This limit does not fully protect against harm to the reproductive system, harm to the developing fetus, and hormone disruption.

ppb = parts per billion

All test results

Date Lab ID Result
2012-02-01AB798540.1000 ppb
2013-02-05AC097300.140 ppb
2013-02-05AC097270.160 ppb
2013-02-05AC097310.150 ppb
2014-01-30AC409320.130 ppb
2014-01-30AC409310.140 ppb
2014-01-30AC409300.130 ppb
2015-01-15AC765840.120 ppb
2015-01-15AC765860.120 ppb
2016-06-27AD419740.120 ppb
2017-01-26AD673230.170 ppb