PFAS Hazard Index (mixture)
PFAS ("forever chemical")
Mixtures of PFAS from firefighting foam, industrial discharge, and landfill leachate.
EPA regulatory status
Legal limit (MCL)
1 unitless
Goal (MCLG)
1 unitless
Hazard Index MCL = 1 (unitless), finalized April 2024, for mixtures of two or more of PFHxS, PFNA, HFPO-DA, and PFBS. Computed as the sum of each measured concentration divided by its health-based level. EPA's May 2025 plan PROPOSES to RESCIND the Hazard Index; the proposal is not final.
Health effects
Captures the combined toxicity of co-occurring PFAS. Component chemicals are linked to liver, thyroid, immune, and developmental effects.
This is general public-health information, not medical advice — consult your physician with any health concerns.
National violations
0
EPA's enforcement data (SDWIS/ECHO) records zero violations of PFAS Hazard Index (mixture)'s rule nationally. See this contaminant's regulatory status above for its current standard and compliance timeline — a zero count is not necessarily an all-clear.
How to remove PFAS Hazard Index (mixture)
anion exchange
NSF/ANSI 53
Frequently asked questions
What is PFAS Hazard Index (mixture)?
PFAS Hazard Index (mixture) is a PFAS ("forever chemical") regulated in US drinking water. Mixtures of PFAS from firefighting foam, industrial discharge, and landfill leachate.
What is the legal limit for PFAS Hazard Index (mixture) in drinking water?
Hazard Index MCL = 1 (unitless), finalized April 2024, for mixtures of two or more of PFHxS, PFNA, HFPO-DA, and PFBS. Computed as the sum of each measured concentration divided by its health-based level. EPA's May 2025 plan PROPOSES to RESCIND the Hazard Index; the proposal is not final.
What health effects does PFAS Hazard Index (mixture) have?
Captures the combined toxicity of co-occurring PFAS. Component chemicals are linked to liver, thyroid, immune, and developmental effects.
How many violations of PFAS Hazard Index (mixture) limits are on record nationally?
EPA's enforcement data (SDWIS/ECHO) records zero violations of PFAS Hazard Index (mixture)'s rule nationally. See this contaminant's regulatory status above for its current standard and compliance timeline — a zero count is not necessarily an all-clear.
How do I remove PFAS Hazard Index (mixture) from my water?
Filter technologies certified to reduce PFAS Hazard Index (mixture) include: reverse osmosis (NSF/ANSI 58), activated carbon (NSF/ANSI 53), anion exchange (NSF/ANSI 53). 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