Disinfection byproducts · in your tap water
Expanded HAA group — broader cancer signal
HAA9 is the expanded group: HAA5 plus four additional acids (bromochloroacetic, bromodichloroacetic, dibromochloroacetic, tribromoacetic). EPA does NOT regulate HAA9 directly — only HAA5 — so there's no federal legal limit, and the EWG guideline is the only meaningful standard. Most NOVA utilities exceed it by hundreds of times.
Federal limit doesn't exist. EWG guideline is what's medically meaningful. Most NOVA utilities are 200×+ over that guideline.
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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.
Confirms HAA9 (the nine acids) is monitored but NOT federally regulated — no MCL.
HAA9 was monitored 2018–2020 to assess occurrence, not for compliance.
Lists several haloacetic acids as 'reasonably anticipated to be human carcinogens.'
Peer-reviewed basis for EWG's health guidelines; finds brominated byproducts the most carcinogenic.
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Get my free water report Book a free checkupThis 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.