Per- and Polyfluoroalkyl Substances (PFAS) In Drinking Water
Regulated PFAS for public water systems, maximum contaminant levels, hazard levels, monitoring, and timeframe for system compliance.
On this page:
- Regulated PFAS
- Maximum Contaminant Levels
- Monitoring and Sampling Timeline
- Health Effects
- Treatment Options
- Related Links
Regulated PFAS
On April 10, 2024, the U.S. Environmental Protection Agency (EPA) announced the final National Primary Drinking Water Regulation for six per- and polyfluoroalkyl substances (PFAS).
- Perfluorooctanoic acid (PFOA)
- Perfluorooctanesulfonic acid (PFOS)
- Perfluorohexanesulfonic acid (PFHxS)
- Perfluorononanoic acid (PFNA)
- Hexafluoropropylene oxide dimer acid (HFPO-DA)
- Mixtures containing at least two or more of PFHxS, PFNA, HFPO-DA, and Perfluorobutane sulfonate (PFBS)
The PFAS rule applies to community and nontransient noncommunity public water systems (PWS) and excludes purchase water systems.
Maximum Contaminant Levels
EPA established individual Maximum Contaminant Levels (MCLs) and finalized health-based, non-enforceable Maximum Contaminant Level Goals (MCLGs). For the mixtures, a Hazard Index MCL will account for the combined and co-occurring levels of these PFAS in drinking water.
Table 1 Maximum contaminant levels and goals for individual compounds and mixtures.
| Compound | Final MCLG (non-enforceable) | Final MCL (enforceable) |
| PFOA |
0 ppt |
4.0 ppt |
| PFOS |
0 ppt |
4.0 ppt |
| PFHxS | 10 ppt | 10 ppt |
| PFNA | 10 ppt | 10 ppt |
| HFPO-DA (also known as GenX Chemicals) | 10 ppt | 10 ppt |
| Mixtures containing two or more of PFHxS, PFNA, HFPO-DA, and PFBS | 1 (unitless) Hazard Index | 1 (unitless) Hazard Index |
Table 2 Descriptions and definitions of contaminant levels, units of measure, and terms
| Maximum Contaminant Level Goal (MCLG): The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety and are non-enforceable public health goals. |
| Maximum Contaminant Level (MCL): The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to MCLGs as feasible using the best available treatment technology and taking cost into consideration. MCLs are enforceable standards. |
| ppt: parts per trillion |
| Hazard Index (HI): The Hazard Index is an approach that is used to understand health risk from a chemical mixture (i.e., exposure to multiple chemicals). The HI is made up of a sum of fractions. Each fraction compares the level of each PFAS measured in the water to the health-based water concentration. |
Hazard Index
Monitoring and Sampling Timeline
By April 26, 2027 - initial monitoring must be completed
- For groundwater community and nontransient noncommunity systems with populations greater than 10,000 and all systems using surface water and groundwater under the influence:
- One sample per entry point, per quarter, collected every two to four months, for four quarters
- For groundwater community and nontransient noncommunity systems with populations less than or equal to 10,000
- One sample per entry point, collected every five to seven months, for a total of two samples
2027 - compliance monitoring begins
- Sampling schedule and frequency based on initial monitoring results
- Once every three years if all regulated PFAS initial monitoring results are below the trigger levels
- Quarterly if any regulated PFAS initial monitoring results are above the trigger levels
2029 - compliance with MCL PFAS requirements begins
Health Effects
Current Understanding of the Human Health and Environmental Risks of PFAS - Find information about health effects related to PFAS on EPA’s webpage.
Treatment Options
Water Treatability Database – Find information about treatment options for contaminants like PFAS in EPA's database.
EPA Fact Sheet - Treatment Options for Removing PFAS in Drinking Water
Related Links
Final PFAS National Primary Drinking Water Regulation - Information about PFAS, monitoring requirements, and calculation of hazard index.
Per- and Polyfluoroalkyl Substances - EPA's explanation about what PFAS are and how the agency is taking action to address them, plus research, data and tools.
Emerging Contaminants in Small or Disadvantaged Communities Grant - Disadvantaged or small (population less than 10,000) communities may be eligible for federal funding available through the Bipartisan Infrastructure Law.
Financial, Managerial and Technical Assistance - TCEQ offers FREE financial, managerial, and technical (FMT) assistance to help public water systems comply with regulations. Contact FMT for help with issues such as, but not limited to preventing operational problems, training about how to comply with rule requirements and performing capacity assessments.
TCEQ's Toxicology division - Toxicology staff help TCEQ make scientifically sound decisions when developing environmental regulations and policy.
Final PFAS Rule Overview - TCEQ presentation on the rule, MCLs, and details about monitoring requirements.