EWG's Tap Water Database



Fremont City

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
20100.413 ppb32ND - 0.830 ppb
20110.327 ppb330.150 ppb - 0.630 ppb
20122.25 ppb330.150 ppb - 5.00 ppb
20130.342 ppb660.120 ppb - 0.620 ppb
20140.335 ppb660.210 ppb - 0.700 ppb
20150.435 ppb660.290 ppb - 0.640 ppb

ppb = parts per billion.

State and national drinking water standards and health guidelines

Health Guideline 0.1 ppb

The 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.

ppb = parts per billion.

EPA Maximum Contaminant
Level (MCL) 3 ppb

The enforceable federal standard that defines the highest level of a contaminant allowed in drinking water.

ppb = parts per billion.

EPA Maximum Contaminant
Level Goal (MCLG)3 ppb

A non-enforceable federal health guideline. For cancer-causing chemicals, these health goals are typically set to zero.

ppb = parts per billion.

All test results

Date Lab ID Result
2010-05-10104071-01B0.410 ppb
2010-06-09104941-010.830 ppb
2011-04-0511-12315-050.150 ppb
2011-05-0911-13246-010.200 ppb
2011-06-0611-13932-030.630 ppb
2012-04-1112-14075-030.150 ppb
2012-05-0912-15295-025.00 ppb
2012-06-0612-16544-051.60 ppb
2013-02-0413-11314-010.130 ppb
2013-04-0113-13943-010.120 ppb
2013-05-0613-15439-010.280 ppb
2013-06-0313-16817-01B0.500 ppb
2013-07-0113-18526-050.620 ppb
2013-10-0113-23328-010.400 ppb
2014-02-0414-11372-010.230 ppb
2014-04-0114-13877-070.230 ppb
2014-05-0514-15302-010.260 ppb
2014-06-0214-16804-01B0.380 ppb
2014-07-0114-18617-030.700 ppb
2014-10-0614-23864-070.210 ppb
2015-02-0315-11275-010.360 ppb
2015-04-0115-13990-010.320 ppb
2015-05-0415-15619-020.290 ppb
2015-06-0115-17183-01C0.590 ppb
2015-07-0815-19413-010.640 ppb
2015-10-0515-24452-010.410 ppb