Atrazine in Drinking Water: Complete Guide (2026)

What is Atrazine and Why Does It Matter?

ATRAZINE: THE HERBICIDE IN YOUR WATER

What Is Atrazine and How Does It Get Into Tap Water?

Atrazine is a herbicide—a chemical used to kill weeds—that's been sprayed on corn and sorghum crops across America since 1958. When it rains, atrazine washes off fields and into groundwater and surface water. From there, it travels into the rivers and aquifers that supply drinking water to millions of people. The Midwest and South are particularly vulnerable because they grow the most corn. Atrazine doesn't break down quickly in water, so it can persist for months or even years, contaminating water supplies long after it's been applied to fields.

The problem is widespread. Out of 2,048 water systems tested, 1,049 systems—about 51%—exceeded the EWG health guideline for atrazine. The average concentration found was 0.165 ppb (parts per billion), but some systems recorded levels as high as 2.55 ppb. To put that in perspective, the EPA's legal limit is 3 ppb, but the EWG—a nonprofit that reviews health science—recommends a much stricter limit of 0.1 ppb based on emerging research.

Health Effects: What the Research Shows

Atrazine is classified as a probable human carcinogen by the EPA, meaning long-term exposure increases cancer risk. Studies have also linked atrazine exposure to reproductive and developmental problems. Research published in environmental health journals shows that atrazine can disrupt hormone systems, even at low doses. The concern is particularly acute for children and pregnant women, whose developing bodies are more sensitive to these disruptions.

At the levels found in many American water systems, the risk may seem small for any individual person. But when you're drinking contaminated water every day for years, the exposure adds up. The EWG's stricter guideline exists precisely because scientists want to protect people from long-term, low-dose exposure. If your water system is one of the 1,049 above the EWG guideline, you're getting more atrazine than health experts recommend.

The Regulatory Gap: EPA vs. EWG Standards

Here's where it gets complicated. The EPA set its legal limit at 3 ppb in 1991, and water systems only have to meet that standard. Your water could be perfectly legal and still exceed EWG's health guideline of 0.1 ppb. This gap exists because the EPA's standard was set decades ago, before some of the newer health research emerged. The EPA reviews its standards periodically, but change happens slowly in federal regulation.

If your water system reports atrazine levels between 0.1 and 3 ppb, your water is legal but potentially riskier than health-focused scientists believe is necessary.

Where Atrazine Contamination Is Worst

Texas leads the nation with 721 water systems exceeding the EWG guideline, followed by Illinois (190), Wisconsin (159), Kansas (155), and Missouri (120). This geographic pattern makes sense: these states grow the most corn and have the most agricultural runoff entering their water supplies. If you live in the Corn Belt or South, atrazine testing should be a priority.

How to Remove Atrazine From Your Water

Granulated activated carbon (GAC) filters are highly effective at removing atrazine. A whole-house carbon filter system can reduce atrazine levels by 85-95%. For drinking water specifically, a point-of-use reverse osmosis system removes up to 99% of atrazine and other herbicides. If you live in one of the high-risk states and your water system reports atrazine detections, installing one of these systems is a practical way to protect your family while you wait for federal standards to catch up with the science.

Start by requesting your local water quality report. If atrazine appears on it, you'll know exactly what you're dealing with—and you can act accordingly.

Regulatory Standards for Atrazine

Cities With the Highest Atrazine Levels

States Most Affected by Atrazine

Frequently Asked Questions

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