Dioxin (2,3,7,8-TCDD) in Drinking Water
EPA limits, health effects, and what to do if your water is affected.
🩨 Health Effects
Dioxin is one of the most toxic substances known. It causes reproductive difficulties and is a known human carcinogen at very low doses. Its MCL of 0.00000003 mg/L (30 parts per quadrillion) is the lowest MCL set by the EPA for any contaminant.
📍 Sources in Water
A byproduct of industrial processes including burning of chlorinated materials, chemical manufacturing, and paper bleaching. Enters water from industrial discharge and contaminated runoff.
✅ What To Do
Dioxin violations in public water systems are extremely rare. Activated carbon filtration can reduce dioxin levels. If you are concerned about dioxin near an industrial site, contact your state environmental agency.
📜 Regulation History
The EPA set the dioxin MCL at 0.00000003 mg/L (30 parts per quadrillion) in 1991, with an MCLG of zero. This is the lowest MCL of any regulated contaminant, reflecting dioxin's extreme toxicity. Dioxin is regulated internationally under the Stockholm Convention on Persistent Organic Pollutants. The WHO also uses very low tolerable intake values for dioxin.
🔬 How To Test Your Water
Testing for dioxin in water is extremely expensive ($500-$1,500+) due to the ultra-low detection limits required (EPA Method 1613). Home test kits are not available. Testing is only relevant near industrial sites or incinerators where dioxin contamination is suspected.
💧 Which Filters Remove Dioxin (2,3,7,8-TCDD)?
Granular activated carbon (GAC) is effective at adsorbing dioxin from water due to its strong affinity for carbon. Reverse osmosis also removes dioxin. Because dioxin binds strongly to particles, sediment filtration provides some removal. Municipal water treatment using powdered activated carbon can address dioxin contamination.
🔗 Related Contaminants
Check your tap water for Dioxin (2,3,7,8-TCDD)
Search your ZIP code to see if your water system has had Dioxin (2,3,7,8-TCDD) violations, plus lead testing results and an overall safety grade.
Search your ZIP code →Data from the EPA's Safe Drinking Water Information System (SDWIS). MCLs reflect minimum federal standards; some contaminants may pose health risks below these thresholds.