What is Atrazine and Why Does It Matter?

Atrazine is one of the most widely used weed killers in the United States. Farmers apply it heavily to corn, sorghum, and sugarcane fields to control broadleaf weeds. After rainfall, it washes off farmland and seeps into streams, rivers, and groundwater — the same sources that feed many public water systems. It's so persistent that it can travel miles from where it was originally sprayed.

Right now, atrazine shows up in 956 water systems across the country. The average level detected is 0.15 parts per billion (ppb), but some systems have recorded concentrations as high as 2.55 ppb. That upper end is worth paying attention to, especially if you have young children at home.

Health researchers have linked atrazine exposure to serious hormonal disruption, even at low levels. The Environmental Working Group (EWG) classifies it as an endocrine disruptor — a chemical that interferes with the body's hormone system. Studies have connected atrazine exposure to reduced fertility, developmental problems in fetuses, and a possible increased risk of certain cancers. Research published in peer-reviewed journals has shown that atrazine can affect fetal development even at concentrations below what the EPA currently considers safe. Children and pregnant women carry the highest risk, since developing bodies are far more sensitive to hormone-disrupting chemicals.

That gap between EPA limits and EWG guidelines tells an important story. The EPA sets atrazine's legal limit at 3 ppb — a standard that hasn't been updated in decades. The EWG's health guideline is far stricter at 0.1 ppb, based on more recent science about hormonal effects at low doses. Of the 956 systems where atrazine was detected, 456 of them — nearly half — already exceed the EWG's health guideline. That means your water could be perfectly legal and still carry levels that independent scientists consider a health concern.

Geography matters a lot with atrazine. Texas leads the country with 348 affected systems, followed by Wisconsin (129), Louisiana (51), Ohio (47), and Kansas (46). That pattern isn't random. These states share something in common: large-scale corn and agricultural farming operations. The Midwest and South are atrazine country. Spring and early summer bring the highest spikes, because that's when farmers apply the herbicide and rain events wash it into waterways. If you live in a rural or semi-rural area near farmland in any of these states, your risk of atrazine exposure through tap water is meaningfully higher than average.

The good news is that atrazine is very removable with the right filtration. Activated carbon filters — especially those using granular activated carbon (GAC) — are effective at reducing atrazine levels significantly. Reverse osmosis (RO) systems go even further, removing up to 99% of atrazine from drinking water. An under-sink reverse osmosis system is one of the most reliable ways to protect your household, particularly if you're in one of the high-exposure states listed above. Echo Water's reverse osmosis systems are independently tested and certified to reduce atrazine along with dozens of other agricultural and industrial contaminants. Standard pitcher filters vary widely in effectiveness, so check the NSF certification label before assuming yours is doing the job. If you want to know exactly what's in your tap water before choosing a filter, Echo Water offers home water testing that gives you a clear, contaminant-by-contaminant picture of what you're actually drinking.

Regulatory Standards for Atrazine

Cities With the Highest Atrazine Levels

States Most Affected by Atrazine

Frequently Asked Questions

Related Contaminant Guides