What is Dalapon* and Why Does It Matter?

Dalapon is an herbicide used primarily to control grassy weeds in agricultural fields, along roadsides, and near irrigation ditches. Farmers have applied it to crops like sugarcane, corn, and flax for decades. After application, dalapon can leach into groundwater or run off into rivers and streams, eventually making its way into public water supplies. It's been detected in 207 water systems across the United States, with an average concentration of 0.341 parts per billion (ppb) and a peak level of 2.9 ppb.

The good news is that no system in this dataset tested above the EPA's legal limit. That said, legal doesn't always mean risk-free. The EPA classifies dalapon as a possible human carcinogen based on animal studies, though the evidence in humans is limited. Animal research has linked high-dose dalapon exposure to liver and kidney stress, as well as changes in blood chemistry (EPA). Long-term, low-level exposure through drinking water is less studied, which is part of why health advocates push for stricter standards. Children and pregnant women are generally considered more vulnerable to pesticide exposure at any level, even when concentrations fall within legal limits.

The EPA's current Maximum Contaminant Level (MCL) for dalapon is 200 ppb — a limit set back in the early 1990s. The Environmental Working Group (EWG) has not published a separate health guideline for dalapon, but the gap between the legal limit and the levels actually detected in water is wide. Average detections sit at just 0.341 ppb, which is roughly 586 times below the legal threshold. That distance offers some reassurance. Still, pesticide regulations often lag behind updated science, and the EPA's limit was established before more recent research on low-dose chemical exposure was available.

Geographically, dalapon detections cluster in agricultural states. Iowa leads the country with 67 affected water systems — not surprising given its dense corn and soybean farming. North Carolina and West Virginia each report 17 affected systems, followed by Texas with 16 and New York with 15. Iowa's dominance reflects the sheer scale of herbicide use across the Midwest, where row crops cover millions of acres and spring rains can push agricultural chemicals into waterways quickly. In North Carolina, tobacco and sweet potato farming contribute to herbicide use in rural areas. West Virginia's detections likely reflect both agricultural runoff and proximity to treated rights-of-way, where dalapon is sometimes used to manage vegetation near roads and pipelines.

If you want to reduce your family's exposure to dalapon, a reverse osmosis (RO) filtration system is your most effective option. Reverse osmosis forces water through a semi-permeable membrane that blocks contaminants at the molecular level, removing up to 99% of pesticide residues including dalapon. Activated carbon filters also reduce herbicide levels, though they're generally less thorough than RO for this class of contaminant. Echo Water's reverse osmosis systems are designed specifically to address the kinds of agricultural chemical exposure common in states like Iowa and Texas, where dalapon detections are highest. If you're on well water in a farming region, testing your water annually is especially important — private wells aren't regulated under federal standards, which means dalapon could be present at any level without any legal requirement to notify you. Knowing what's in your water is always the first step toward protecting your family.

Regulatory Standards for Dalapon*

Cities With the Highest Dalapon* Levels

States Most Affected by Dalapon*

Frequently Asked Questions

Related Contaminant Guides