Chloroform
Chloroform is the most common trihalomethane and the surrogate the NSF/ANSI 53 VOC test uses for the family. It is regulated as part of total trihalomethanes (TTHM limit 80 ppb). Its EPA health goal (MCLG) is 0.07 mg/L.
EPA MCLG
0.07 mg/L
The level in drinking water below which there is no known or expected risk to health. This is a goal, not an enforceable limit.
Health Effects
Long-term exposure is associated with an increased risk of bladder cancer at the population level; the EPA and IARC classify it as a possible or probable human carcinogen. Liver, kidney, and central-nervous-system effects have been observed at high doses. The risk is chronic and lifetime, not acute.
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 Chloroform result safe? Get a free reading
The EPA MCLG for Chloroform is 0.07 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 Chloroform
How do I get rid of Chloroform in drinking water?
For Chloroform, the verified treatment is activated carbon. Activated carbon is a conditional treatment. Requires an NSF/ANSI 53 TTHM-certified carbon and adequate contact time; carbon adsorbs TTHM but breaks through over time. EPA's municipal BAT is GAC10/GAC20 with enhanced coagulation or softening.
Source: NSF/ANSI 53 (TTHM reduction) / EPA Stage 1 & 2 D/DBP Rule, 40 CFR 141.64
What filter certification covers Chloroform?
Activated carbon is certified under NSF/ANSI 53. Check that the certification listing names Chloroform or its group: a certification to a standard is not a certification for every contaminant in it.
Source: NSF/ANSI 53 (TTHM reduction) / EPA Stage 1 & 2 D/DBP Rule, 40 CFR 141.64
Does a basic water filter pitcher remove Chloroform?
Only if it is certified for it. A basic pitcher is an activated-carbon device and carbon does adsorb Chloroform, but only a pitcher certified under NSF/ANSI 53 for this reduction has been tested to do it, and the cartridge breaks through as it loads — so replacement on schedule is part of the answer. An NSF/ANSI 42 certification, which most pitchers carry, covers taste and odor only and says nothing about Chloroform.
Source: NSF/ANSI 53 (TTHM reduction) / EPA Stage 1 & 2 D/DBP Rule, 40 CFR 141.64
Does boiling water remove Chloroform?
Mostly, from the water you drink — and this is the half of the disinfection-byproduct group where that is true. Trihalomethanes are volatile, so heating drives Chloroform out of the water rather than destroying it: EPA measured volatilization losses approaching 75% when water was boiled even for brief periods, and 90% when the boiled water was poured and served. It leaves as vapour into the room, which is why the cited EPA work is about ingestion exposure — it lowers what you swallow, not what the household breathes. Open containers lost more than closed ones, because a lid traps the vapour. None of this is advice to boil your water: boiling does nothing for the non-volatile half of this group and can raise haloacetic acids where residual chlorine is present, so it is no treatment for disinfection byproducts as a group.
Get Chloroform Updates
Research updates, regulation changes, and filter recommendations — in your inbox.
Free forever. Unsubscribe anytime. We never share your email.
Is Chloroform in your water?
Chloroform has been recorded above its health guideline in 14 cities, serving 0.0M people. Each system below was judged against a goal of 70 PPB.
Most affected systems, by population served
- Liberty, OK8,370 people served82.4 PPBgoal 70 PPB
- Mounds, OK8,370 people served82.4 PPBgoal 70 PPB
- Winchester, OK8,370 people served82.4 PPBgoal 70 PPB
- Cleveland, OK3,262 people served113 PPBgoal 70 PPB
- Rolling Fork, MS2,685 people served74.4 PPBgoal 70 PPB
- Schulter, OK1,890 people served91.3 PPBgoal 70 PPB
- Barnsdall, OK1,243 people served93.1 PPBgoal 70 PPB
- Stringtown, OK1,105 people served97.8 PPBgoal 70 PPB
- Weleetka, OK998 people served72.8 PPBgoal 70 PPB
- McCurtain, OK560 people served85.2 PPBgoal 70 PPB
and 4 more cities with a recorded result above the guideline
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 Chloroform result on file at all. We publish a level only where a system reported one.
Check your city or ZIP code for Chloroform
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 MCLG
The EPA MCLG is the level of a contaminant in drinking water below which there is no known or expected risk to health. It is a non-enforceable public health goal, and is often stricter than the legal limit (MCL) water systems must meet.
Contaminant Type
Chloroform is classified as a Disinfection Byproducts contaminant.
Related Disinfection Byproducts Contaminants
Check Your Water
Find out if Chloroform is in your tap water.
Search cities for Chloroform 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.