Disinfection Byproduct
Haloacetic Acids (HAA9) in your water
Health effects
HAA9 is a broader measure of nine haloacetic-acid disinfection byproducts, of which only five are federally regulated. They form the same way as HAA5 - chlorine reacting with organic matter - and carry similar long-term cancer-risk concerns. The wider HAA9 group captures byproducts the federal standard does not.
The guideline vs. the legal limit
The federal legal limit is the maximum allowed by law. The EWG health guideline is what independent scientists consider safe — it is often far stricter.
Health guideline (EWG)
0.06 ppb
Federal legal limit (MCL)
No federal limit set
Source: EWG Tap Water Database & EPA MCLs · 2026
What removes Haloacetic Acids (HAA9)
We're still cataloging certified systems for Haloacetic Acids (HAA9). A free water test is the fastest way to get a matched recommendation.
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Is Haloacetic Acids (HAA9) in your water?
Check your city's public record, then book a free 30-minute test to confirm what's in your home.