Picloram in Drinking Water: Complete Guide (2026)

What is Picloram and Why Does It Matter?

# Understanding Picloram in Your Drinking Water

Picloram is a herbicide—a chemical designed to kill weeds—that's widely used in agriculture and by land managers to control unwanted vegetation. When farmers spray picloram on crops or when it's applied to roadsides and forests, some of it eventually makes its way into groundwater and surface water sources. Rain washes residue from treated fields into streams and aquifers. Over time, picloram can persist in water because it breaks down slowly in the environment. Our analysis found picloram in 206 water systems across the United States, with concentrations ranging from undetectable levels up to 3.1 ppb (parts per billion). While the average level sits at just 0.084 ppb, that maximum reading shows the chemical can accumulate significantly in certain areas.

The health effects of picloram exposure depend on how much you consume and for how long. At low levels, picloram causes minimal immediate harm—which is why it's often overlooked. However, the Environmental Working Group (EWG) has raised concerns about long-term exposure, particularly for children whose developing bodies may be more vulnerable to toxic effects. Animal studies suggest picloram can affect the nervous system and digestive health at high doses, though human studies are limited. The EPA currently allows picloram in drinking water at levels up to 500 ppb, a standard set decades ago and considered outdated by many health advocates. The EWG's health guideline is significantly stricter: 0.35 ppb. This gap matters. None of the 206 systems we detected exceeded the EPA limit, but many would exceed the EWG guideline—highlighting how federal standards lag behind emerging science.

The regulatory picture for picloram remains incomplete. The EPA hasn't updated its drinking water standard since 1992, despite growing evidence that lower exposures may pose risks. Some states have adopted their own limits, but most rely on the federal standard. This means homeowners in areas with picloram contamination may not receive official warnings, even if levels concern health-conscious families. The good news: picloram isn't a "forever chemical" like PFOA. It does eventually break down, so contamination doesn't persist indefinitely if the source is removed.

Texas leads the nation with picloram detections in 84 water systems—a direct result of the state's massive agricultural footprint, especially in cotton and grain production. Iowa ranks second with 26 systems affected, reflecting heavy herbicide use in corn and soybean farming. Louisiana, Florida, and West Virginia round out the top five, each with 11-12 detections. The pattern is clear: picloram shows up wherever intensive agriculture dominates. In the Midwest, spring application for crop season explains seasonal spikes. In Texas, year-round farming means ongoing exposure risk.

Removing picloram from drinking water requires specific filtration approaches. Activated carbon filters work well for picloram—they can remove 85-95% of the chemical if properly maintained and replaced regularly. Reverse osmosis systems are even more effective, removing up to 99.9% of picloram along with other herbicides. If you live in Texas, Iowa, or another agricultural region and want to reduce herbicide exposure, these systems provide reliable protection. Pitcher filters and basic sediment filters won't work—picloram is dissolved in water, not suspended as particles. For the most targeted protection, consider having your water tested specifically for herbicides. If picloram appears in your results above 0.35 ppb (the EWG guideline), a dedicated carbon or reverse osmosis system makes sense for your family's drinking water.

Regulatory Standards for Picloram

Cities With the Highest Picloram Levels

States Most Affected by Picloram

Frequently Asked Questions

Related Contaminant Guides