Total Haloacetic Acids (HAA5)
HAA5 is the sum of five haloacetic acids formed when chlorine reacts with organic matter. Unlike trihalomethanes they are non-volatile, so they are an ingestion concern rather than a shower concern. The EPA limits HAA5 to 60 ppb (0.060 mg/L).
EPA MCL
0.06 mg/L
EPA has not set a health goal (MCLG) for this contaminant. This is the enforceable limit water systems must meet.
Health Effects
Long-term exposure is associated with an increased cancer risk; dichloroacetic acid, one of the five, is classified a probable human carcinogen. The risk is chronic and lifetime rather than acute.
Source: EPA — IRIS Chemical Assessment Summary — Dichloroacetic Acid (retrieved 2026-07-27)
Common Sources
- Byproduct of disinfecting drinking water with chlorine
- Formed when chlorine reacts with natural organic matter such as decaying leaves, runoff, and algae
- Levels are highest in warm-season surface water
Is your Total Haloacetic Acids (HAA5) result safe? Get a free reading
The EPA MCL for Total Haloacetic Acids (HAA5) is 0.06 mg/L. Upload your water test (PDF or a photo) and we'll email a plain-English reading of where your result lands — and every other number — free. Educational only, no medical claims.
Your upload also helps us keep local water data accurate — we only ever share anonymized, area-level summaries.
Upload my testHow to Remove Total Haloacetic Acids (HAA5)
How do I get rid of Total Haloacetic Acids (HAA5) in drinking water?
For Total Haloacetic Acids (HAA5), the verified treatment is activated carbon. Activated carbon is a conditional treatment. EPA's designated BAT is plant-scale: enhanced coagulation or softening plus GAC10, nanofiltration below 1000 Da, or GAC20. At point of use carbon adsorbs haloacetic acids but breaks through as the bed loads, and no certified product in our index claims HAA5 reduction — so no certified home removal can be asserted.
Source: EPA 40 CFR 141.64(b) — Stage 1 & 2 D/DBP Rule (HAA5 MCL 0.060 mg/L; BAT as quoted)
What filter certification covers Total Haloacetic Acids (HAA5)?
None. No NSF/ANSI standard certifies a filter for Total Haloacetic Acids (HAA5), and no certified product in our index claims this reduction. That is a verified answer rather than a hole in our data — the same index does carry certified trihalomethane-reduction claims, so the search ran and came back empty for this one. A filter advertised as removing Total Haloacetic Acids (HAA5) is making a claim no certifier has listed.
Source: EPA 40 CFR 141.64(b) — Stage 1 & 2 D/DBP Rule (HAA5 MCL 0.060 mg/L; BAT as quoted)
Does a basic water filter pitcher remove Total Haloacetic Acids (HAA5)?
Only in principle, and no pitcher is certified to prove it. A basic pitcher is an activated-carbon device, and activated carbon is the indicated method for Total Haloacetic Acids (HAA5) — but no certified product in our index claims this reduction, so no pitcher has been tested against it. An NSF/ANSI 42 certification, which most pitchers carry, covers taste and odor and says nothing about Total Haloacetic Acids (HAA5).
Source: EPA 40 CFR 141.64(b) — Stage 1 & 2 D/DBP Rule (HAA5 MCL 0.060 mg/L; BAT as quoted)
Does boiling water remove Total Haloacetic Acids (HAA5)?
Largely no, and this is where Total Haloacetic Acids (HAA5) differs from the trihalomethanes on the same water report. Haloacetic acids are non-volatile — an ingestion concern rather than a shower concern — so heating does not drive them off: in the 2024 comparison of boiling's effect on disinfection byproducts, trihalomethanes were markedly decreased while haloacetic acids were "reduced the least". Residual chlorine can make it worse rather than better: chlorine from 0.1 to 5.0 mg/L could increase haloacetic-acid levels, likely through reaction of organic matter with chlorine at elevated temperatures — chloroform down about 75%, dihaloacetic acids up 58–68% in the study that measured both directions at once. Boiling is not a treatment for Total Haloacetic Acids (HAA5).
We name no filter for Total Haloacetic Acids (HAA5), because no NSF/ANSI standard certifies one for it. There is nothing to link to here, and a link would be the wrong answer.
Get Total Haloacetic Acids (HAA5) Updates
Research updates, regulation changes, and filter recommendations — in your inbox.
Free forever. Unsubscribe anytime. We never share your email.
Is Total Haloacetic Acids (HAA5) in your water?
Total Haloacetic Acids (HAA5) has been recorded above its legal limit in 9 cities, serving 0.0M people. Each system below was judged against a limit of 0.06 PPM.
Most affected systems, by population served
- Kotzebue, AK3,234 people served0.0702 PPMlimit 0.06 PPM
- Carrabelle, FL2,627 people served0.074 PPMlimit 0.06 PPM
- Wainwright, OK2,550 people served0.067 PPMlimit 0.06 PPM
- Proctor, VT2,000 people served0.0621 PPMlimit 0.06 PPM
- Schulter, OK1,890 people served0.0622 PPMlimit 0.06 PPM
- Mars Hill, ME1,500 people served0.061 PPMlimit 0.06 PPM
- Barnsdall, OK1,243 people served0.0705 PPMlimit 0.06 PPM
- Thorne Bay, AK470 people served0.195 PPMlimit 0.06 PPM
- Kake, AK415 people served0.079 PPMlimit 0.06 PPM
These are the largest systems that reported a result above the guideline — not the highest results. A city missing from this list has not been shown to be clean: it may have no Total Haloacetic Acids (HAA5) result on file at all. We publish a level only where a system reported one.
Check your city or ZIP code for Total Haloacetic Acids (HAA5)
Part of a group: disinfection byproducts
This contaminant is rarely measured on its own. Disinfection byproducts in drinking water covers the whole group — what they are, which limits are enforceable, and where they come from.
Others in this group
About the EPA MCL
This is the enforceable federal limit water systems must meet. EPA has not set a separate non-enforceable health goal (MCLG) for this contaminant.
Contaminant Type
Total Haloacetic Acids (HAA5) is classified as a Disinfection Byproducts contaminant.
Related Disinfection Byproducts Contaminants
Check Your Water
Find out if Total Haloacetic Acids (HAA5) is in your tap water.
Search cities for Total Haloacetic Acids (HAA5) dataTest Your Water for This Contaminant
Public water reports may not test frequently enough or at your specific tap. Professional home testing provides current, location-specific results.
SimpleLab
Advanced Home Water Test
$269
Comprehensive water analysis testing over 200 contaminants including bacteria, heavy metals, and chemical compounds.
Tap Score
Advanced Microplastics Test
$829
Cutting-edge testing for microplastics particles in drinking water using advanced laboratory techniques.
Tap Score
Haloacetic Acids (HAA9) Test
$275
Tests for disinfection byproducts formed when chlorine reacts with organic matter in water treatment.
Get the Weekly Water Brief
One email a week on water testing, treatment, and what water-quality data means for your home.
One email a week. Unsubscribe anytime.