Diquat
Diquat·Affects kidneys, liver
A non-selective contact herbicide used to control aquatic weeds, desiccate crops before harvest, and clear vegetation. EPA-regulated due to kidney and liver toxicity.
Diquat
EPA limit
0.02 mg/L (MCL)
Most at risk
Rural well-water households, residents near treated lakes and ponds, agricultural workers
Found in
City water · Well water
AquaOx filters
YesActivated coconut shell carbon
What it does to you
Health effects
Diquat's primary chronic effects target the kidneys and liver. Long-term animal studies show kidney tubular damage and liver enzyme changes at moderate exposures, and the EPA set the drinking water standard based on these endpoints.
Acute exposure damages the gastrointestinal tract and can cause severe and sometimes fatal poisoning through ingestion of concentrated product. The compound also causes cataracts at chronic moderate exposures in animal studies, which is the basis for occupational exposure limits.
Unlike its chemical cousin paraquat, diquat does not concentrate in the lungs and is not as acutely fatal, but it is still classified as highly toxic and requires restricted-use certification for application.
Where it comes from
How it gets into your water
Diquat is sprayed on aquatic weeds in lakes, ponds, and irrigation channels, applied as a pre-harvest desiccant on potatoes and other crops, and used for industrial vegetation control. It binds extremely tightly to soil and sediment, so groundwater contamination is uncommon, but direct application to surface water sources is the primary pathway into drinking water.
Public utilities drawing from lakes or reservoirs treated for aquatic weed control may detect diquat for weeks after application. Concentrations decline rapidly as the compound binds to sediment.
Spray drift from agricultural and right-of-way applications can also contaminate nearby surface water.
Aquatic weed control
Direct application to lakes and ponds
Pre-harvest desiccation
Potato and other crop applications
Treated surface water
Reservoirs and irrigation canals
Find out for yourself
Is it in your water?
Public utilities test for diquat and report results in their annual Consumer Confidence Report. Detections are uncommon but more likely in systems drawing from lakes or reservoirs treated for aquatic weeds.
Private well owners are generally at low risk for diquat because the compound binds tightly to soil and does not migrate readily into groundwater. Households drawing surface water directly from a treated pond or lake should test before and after the treatment season.
The fix
How AquaOx filters it
Diquat is filtered efficiently by activated carbon. The coconut shell carbon stage in The AquaOx adsorbs diquat molecules as water passes through, with independent testing showing high reduction rates.
For households drawing from treated surface water sources, we recommend pairing The AquaOx with our FE Edition or RE Edition if iron or hydrogen sulfide is also present, and adding the under-sink RO for additional drinking-water polish.