Disinfection Byproduct
Haloacetic Acids (HAA9) in your water
Is Haloacetic Acids (HAA9) in drinking water dangerous?
It depends on the level and how long you're exposed. The EPA has set no federal legal limit for Haloacetic Acids (HAA9), but health-based goals (EPA MCLG / WHO) are often stricter, at 0.06 ppb. Meeting the legal limit isn't the same as zero risk — test your water to know your level.
How do you remove Haloacetic Acids (HAA9) from water?
Haloacetic Acids (HAA9) is treated by Reverse Osmosis and Whole-House Carbon Filter. Choose a system independently certified to NSF/ANSI standards to reduce Haloacetic Acids (HAA9), and test your water first to confirm the level.
Source: EPA MCL / MCLG; WHO guidelines; NSF/ANSI · 2026
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 health-based goal vs. the legal limit
The federal legal limit (MCL) is the maximum allowed by law. The health-based goal (EPA MCLG / WHO) is a health target — it is often stricter than the legal limit, and it is not itself a legal limit.
Health-based goal (EPA MCLG / WHO)
0.06 ppb
Federal legal limit (MCL)
No federal limit set
Source: EPA MCL / MCLG; WHO guidelines · 2026
Not affiliated with or endorsed by EWG.
What removes Haloacetic Acids (HAA9)
Semipermeable membrane filtration
Reverse Osmosis
Pushes water through a fine membrane that removes the dissolved solids most filters miss.
Look for: NSF/ANSI 58 certification
How it works→Activated carbon adsorption
Whole-House Carbon Filter
A point-of-entry carbon bed that strips chlorine, chloramine, and chemical taste from every tap.
Look for: NSF/ANSI 42 certification
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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.