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Disinfection byproducts · in your tap water

Dichloroacetic acid (DCA)

Part of the HAA family

Reviewed by Tyler Griffin — Founder, SwiftPro Heating, Cooling & Plumbing

FamilyDisinfection byproducts
Where it comes fromChlorine + organic matter in source water
Best fixActivated carbon

What it is

One of the five regulated haloacetic acids. Forms during chlorine disinfection.

Same family as TTHMs. Same fix.

What you might notice & the health concern

Where it comes from

What actually removes it

Not sure which system you need? Our reverse-osmosis and whole-home pages compare the options, or book a free Home Water Checkup and we'll test your actual tap.

The research

Every source below was checked to make sure the link works and backs the claim it's next to. These are the primary regulators and peer-reviewed studies — not our opinion.

1
Dichloroacetic Acid — IARC Monographs Vol. 106 ↗ IARC / NCBI Bookshelf

IARC classifies DCA as Group 2B (possibly carcinogenic; liver tumors in animals).

2
Haloacetic Acids Found as Water Disinfection Byproducts — 15th Report on Carcinogens ↗ U.S. National Toxicology Program

Lists several haloacetic acids as 'reasonably anticipated to be human carcinogens.'

3
Stage 1 and Stage 2 Disinfectants and Disinfection Byproducts Rules ↗ U.S. EPA

The federal rules that set the TTHM (80 ppb) and HAA5 (60 ppb) drinking-water limits.

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This page is general water-quality education, not medical advice. Health classifications and limits are attributed to the EPA, EWG, IARC, ATSDR/CDC, WHO and the cited studies. Contaminant levels vary by water system and home — the only way to know what's in your water is to test it. Prepared by SwiftPro Heating, Cooling & Plumbing.