Haloacetic Acids (HAA5)
disinfection byproduct
Byproduct formed when chlorine disinfectant reacts with natural organic matter in the water.
EPA regulatory status
Legal limit (MCL)
60 ppb
Goal (MCLG)
Not set
MCL 60 ppb (0.060 mg/L), enforced as a Locational Running Annual Average (LRAA) under the Stage 2 D/DBP Rule — not an instantaneous limit. HAA5 = the sum of five haloacetic acids.
Health effects
Long-term exposure is associated with an increased risk of cancer.
This is general public-health information, not medical advice — consult your physician with any health concerns.
National violations
69,754
EPA's enforcement data (SDWIS/ECHO) records 69,754 violations of Haloacetic Acids (HAA5)'s rule nationally.
How to remove Haloacetic Acids (HAA5)
Frequently asked questions
What is Haloacetic Acids (HAA5)?
Haloacetic Acids (HAA5) is a disinfection byproduct regulated in US drinking water. Byproduct formed when chlorine disinfectant reacts with natural organic matter in the water.
What is the legal limit for Haloacetic Acids (HAA5) in drinking water?
MCL 60 ppb (0.060 mg/L), enforced as a Locational Running Annual Average (LRAA) under the Stage 2 D/DBP Rule — not an instantaneous limit. HAA5 = the sum of five haloacetic acids.
What health effects does Haloacetic Acids (HAA5) have?
Long-term exposure is associated with an increased risk of cancer.
How many violations of Haloacetic Acids (HAA5) limits are on record nationally?
EPA's enforcement data (SDWIS/ECHO) records 69,754 violations of Haloacetic Acids (HAA5)'s rule nationally.
How do I remove Haloacetic Acids (HAA5) from my water?
Filter technologies certified to reduce Haloacetic Acids (HAA5) include: activated carbon (NSF/ANSI 53), reverse osmosis (NSF/ANSI 58). Look for a filter independently certified against the specific NSF/ANSI standard for this contaminant — general "reduces contaminants" marketing claims are not the same as a contaminant-specific certification.
Source: EPA National Primary Drinking Water Regulations · Data as of 2026-07-16