Chlorine and chlorination byproducts (trihalomethanes)
Water disinfection
🟡 Several human studies point the same way, with a plausible biological mechanism, but the evidence is not yet conclusive.
Share this factsheet
In brief
chlorine in drinking water: this page reviews Chlorine and chlorination byproducts (trihalomethanes) (Water disinfection) — documented mechanism, everyday exposure situations and possible alternatives. Level of evidence: Probable.
- Where it's found
- Treated tap water, noticeable chlorine smell or taste.
- Suspected mechanism
- Chlorine reacts with organic matter in water and forms trihalomethanes; some studies link these to adverse pregnancy outcomes.
- Suggested alternative
- Let water sit uncovered for a few hours, or filter with activated carbon: this reduces chlorine (but not nitrates or PFAS).
- Source
- Studies on trihalomethanes and pregnancy outcomes.
Frequently asked questions
Chlorine and chlorination byproducts (trihalomethanes): how is it linked to infertility?
Chlorine reacts with organic matter in water and forms trihalomethanes; some studies link these to adverse pregnancy outcomes.
Where is Chlorine and chlorination byproducts (trihalomethanes) found in everyday life?
Treated tap water, noticeable chlorine smell or taste.
How can exposure to Chlorine and chlorination byproducts (trihalomethanes) be reduced?
Let water sit uncovered for a few hours, or filter with activated carbon: this reduces chlorine (but not nitrates or PFAS).
What is the level of evidence for Chlorine and chlorination byproducts (trihalomethanes)?
Probable. Several human studies point the same way, with a plausible biological mechanism, but the evidence is not yet conclusive.
Map your everyday exposures in about ten minutes.
Take the questionnaireShare this factsheet
Related factors
Including a factor does not mean it causes infertility: it is simply worth monitoring, depending on its level of evidence.
Content last updated: September 14, 2026