Dichloroacetic Acid
DCAA·Affects liver, reproductive
One of the five haloacetic acids regulated as a group in chlorinated water. Forms in the same disinfection reaction that produces THMs.
DCAA
EPA limit
0.060 mg/L (combined HAA5)
Most at risk
Long-term consumers, pregnant women
Found in
City water
AquaOx filters
YesActivated coconut shell carbon
What it does to you
Health effects
Dichloroacetic acid (DCAA) is regulated by the EPA as one of the HAA5 group at a combined limit of 60 ppb. It is classified by the EPA as a likely human carcinogen, with the liver as the primary target organ. Animal studies show liver tumors at chronic high doses, and human epidemiology associates HAA exposure with increased bladder cancer risk.
Reproductive and developmental effects are the second major concern. The EPA cites evidence of adverse outcomes including impaired fetal development in animal models, which is why pregnant women are an at-risk group.
Unlike THMs, DCAA is not volatile, so inhalation and shower-vapor exposure are not the dominant routes. Direct ingestion through drinking and cooking water is the exposure pathway the MCL targets.
Where it comes from
How it gets into your water
DCAA forms in the same chlorination chemistry that produces THMs. When chlorine added at the treatment plant reacts with naturally-occurring organic matter (humic and fulvic acids from leaves, soil, algae), part of the reaction goes to THMs and part to HAAs. DCAA and trichloroacetic acid (TCAA) typically dominate the HAA5 mix in low-bromide source waters.
The reaction continues in distribution pipes, so DCAA can be higher at the end of the line than near the plant. Warmer water and higher organic loads in late summer and early fall raise levels.
Chlorinated treatment plants
Chlorine reacts with organic matter
Distribution pipes
Reaction continues during transit
Tap water
Ingested in drinking and cooking water
Find out for yourself
Is it in your water?
DCAA is present in nearly all chlorinated US municipal supplies, since the reaction that creates it is the same one that disinfects the water. Your utility's annual Consumer Confidence Report (CCR) reports total HAA5 and may break out individual species.
Levels rise seasonally with warmer water and higher organic content. Households at the periphery of the distribution network typically see the highest residuals.
The fix
How AquaOx filters it
Activated carbon adsorbs HAAs, including DCAA. The catalytic and coconut-shell carbon stages in AquaOx systems are sized to capture the full HAA5 family across normal residential flow rates.
Because DCAA exposure is primarily through ingestion rather than shower vapor, both whole-house and point-of-use filters help; the advantage of whole-house is that every tap, including kitchen, ice maker, and coffee maker, delivers filtered water without remembering which faucet to use.
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