Is atrazine in my tap water?

If you live in a Corn Belt state — Iowa, Illinois, Indiana, Kansas, Nebraska, Missouri, Ohio — there is a meaningful chance atrazine is detectable in your water, particularly in spring. Check your utility's Consumer Confidence Report for atrazine test results. The MCL is measured as an annual average, so individual spring samples can legally exceed 3 ppb. Private well owners in agricultural areas should test specifically for atrazine — standard well tests do not include it.

Why is atrazine banned in Europe but still used in the U.S.?

The European Union banned atrazine in 2004 under its precautionary principle — the EU found it impossible to keep atrazine below 0.1 ppb in groundwater, and that level was the EU's threshold for pesticide approval. The U.S. EPA has reviewed atrazine repeatedly and maintained its 3 ppb MCL, citing that health risks at that level are not definitively established at the dose-response level required for U.S. regulatory action. The 30x difference between the EU standard (0.1 ppb) and the U.S. MCL (3 ppb) reflects fundamentally different regulatory philosophies on burden of proof.

Does atrazine cause cancer?

The evidence is suggestive but not conclusively established at drinking water concentrations. Atrazine is classified as 'not likely to be carcinogenic to humans' by the EPA under its current assessment, though independent researchers and the EWG dispute this characterization. Studies have found associations between atrazine exposure and ovarian, breast, and prostate cancers in highly exposed occupational and agricultural populations. The IARC has not classified atrazine definitively as a human carcinogen. The better-established concern is endocrine disruption at low concentrations.

What filter removes atrazine from water?

Activated carbon filtration is the most widely available and cost-effective option for atrazine — granular activated carbon (GAC) and carbon block filters both adsorb atrazine effectively. Look for NSF/ANSI 53 certification specifically for atrazine reduction. Reverse osmosis also removes atrazine as part of its broad contaminant reduction profile. Standard pitcher filters with carbon may help but should be verified for atrazine certification specifically.

Is atrazine safe for pregnant women?

At EPA-regulated levels there is no confirmed acute harm, but the precautionary evidence is concerning. Atrazine crosses the placenta, and some epidemiological studies link maternal atrazine exposure to low birth weight and hormonal disruption in developing fetuses. Given the EU's precautionary ban and the endocrine disruption evidence, pregnant women in agricultural water areas may consider using a certified activated carbon or reverse osmosis filter for drinking and cooking water.

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Atrazine in Drinking Water

Atrazine is one of the most widely used herbicides in the United States — applied to corn, sorghum, and sugarcane across the Midwest — and is the most commonly detected pesticide in U.S. groundwater and streams. The EPA MCL is 3 ppb. It was banned in the European Union in 2004 over environmental and health concerns. Atrazine is an endocrine disruptor linked to hormonal disruption, reproductive effects, and possible cancer risk at levels found in drinking water.

Quick Answer

Atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) is a selective herbicide applied primarily to corn to control broadleaf and grass weeds. Approximately 70 million pounds are applied annually in the U.S., concentrated in the Corn Belt states of Iowa, Illinois, Indiana, Kansas, Nebraska, and Missouri. Atrazine is highly mobile in soil and readily leaches into groundwater and surface water. It persists in the environment for months and is detected year-round in agricultural water supplies, with peaks in spring following pre-emergent application.

Why Is Atrazine in Drinking Water a Concern?

The Environmental Working Group has documented atrazine in the tap water of 30 million Americans at levels above what EWG considers health-protective. A 2010 Natural Resources Defense Council analysis found atrazine in the tap water of 153 public water systems across the Midwest at levels exceeding the EPA limit. Research by University of California, Berkeley biologist Tyrone Hayes found that atrazine chemically castrates male frogs at concentrations as low as 0.1 ppb — well below the 3 ppb MCL. The European Union banned atrazine in 2004 citing groundwater ubiquity and endocrine disruption concerns that could not be adequately mitigated.

Rural residents and private well owners in corn-growing regions of the Midwest — Iowa, Illinois, Indiana, Kansas, Nebraska, Ohio, Missouri — face the highest exposure. Municipal water customers in agricultural areas may also receive water that exceeds or approaches the MCL seasonally, particularly in late spring and early summer following herbicide application. See the [Kansas well water guide](/well-water/kansas) for state-specific context on pesticide contamination.

Health Effects of Atrazine in Drinking Water

Endocrine disruption — atrazine interferes with hormone synthesis and signaling at low concentrations; disrupts estrogen and testosterone pathways

Reproductive effects — reduced fertility, altered menstrual cycles, and hormonal imbalances in women; reduced sperm quality in men at elevated exposure

Possible increased ovarian, breast, and prostate cancer risk with long-term exposure — IARC classification under review

Developmental effects in fetuses — atrazine crosses the placenta; associated with low birth weight and birth defects in some epidemiological studies

Thyroid disruption with chronic exposure

No established acute toxicity at concentrations found in drinking water — all concerns are chronic/long-term

How Does Atrazine Get Into Drinking Water?

Agricultural herbicide application to corn — the dominant source; approximately 70 million pounds applied annually in the U.S.

Sorghum and sugarcane production in Kansas, Oklahoma, and the Gulf Coast

Surface water runoff following spring pre-emergent application — highest levels April through June

Groundwater leaching through sandy or porous soils common in Corn Belt states

Irrigation return flows carrying atrazine residues back to water sources

Regulatory Limit

EPA Maximum Contaminant Level (MCL)

3 ppb (0.003 mg/L)

The EPA MCL for atrazine is 3 parts per billion (0.003 mg/L), set in 1991 and measured as a running annual average rather than individual samples. This averaging method allows seasonal spikes well above 3 ppb as long as the annual average stays below the limit — meaning spring samples can legally exceed the MCL. The EPA has reviewed atrazine multiple times and maintained the 3 ppb standard, citing the cost of lower limits for water systems. The EWG recommends a health-protective limit of 0.1 ppb. The EU banned atrazine entirely in 2004 because the substance could not be kept below 0.1 ppb in groundwater.

How to Test for Atrazine in Your Water

Atrazine is tested by public water systems in agricultural areas and reported in Consumer Confidence Reports. The MCL is measured as an annual running average, so seasonal peaks may not be reflected in annual data. Well owners in agricultural regions should test specifically for atrazine and other herbicides using a certified laboratory panel — standard bacterial and nitrate tests do not screen for pesticides. Herbicide panels typically cost $50–$150. Testing in late spring (May–June) when post-rain runoff is highest captures peak exposure. See [how to test well water](/guides/how-to-test-well-water) for general testing guidance.

How to Remove Atrazine from Drinking Water

Best filter for Atrazine: Reverse Osmosis Filtration — also effective: Activated Carbon

These treatment methods have demonstrated effectiveness for Atrazine removal.

Reverse Osmosis

Reverse osmosis (RO) is the most comprehensive point-of-use water treatment technology available for residential use. It removes 90–99% of dissolved contaminants including PFAS, lead, arsenic, nitrates, and disinfection byproducts by forcing water through a semi-permeable membrane with pores of approximately 0.0001 microns.

PFAS / PFOA / PFOS — 90–99% removalLead — 95–99% removal

Activated Carbon

Activated carbon is the most widely used residential water treatment technology. It removes chlorine, taste and odor compounds, disinfection byproducts, many volatile organic compounds (VOCs), and — with NSF/ANSI 53 certification — lead and some PFAS. It is available as pitcher filters, under-sink units, and whole-house systems.

Chlorine and chloramine — virtually complete removalTaste and odor compounds — highly effective

Frequently Asked Questions

Reverse Osmosis Filtration

Removes: Atrazine

Activated Carbon Filtration

Removes: Atrazine

Nitrates in Drinking Water

Agricultural Chemicals

Data Sources & Provenance

All data on this page is sourced from official U.S. government or public datasets.

EPA Drinking Water Contaminant InformationView source

ATSDR ToxFAQs / Toxicological ProfilesView source

EPA SDWIS — violation and detection dataView source

Last updated: 2026-04-30

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