PFAS in Drinking Water—Group A Public Water System Information and Support

The State Board of Health (Board) revised the WAC 246-290 Group A Drinking Water Rules in December 2021, to require public water systems to monitor for select per- and polyfluoroalkyl substances (PFAS) using specific analytical methods. WAC 246-290 established state action levels (SALs) for five PFAS contaminants: PFOA, PFOS, PFHxS, PFNA, and PFBS.

The Environmental Protection Agency (EPA) released their final PFAS regulation on April 26, 2024. After the release of EPA's PFAS rule, the Board began the process to adopt the federal rule while maintaining our current rule's public health protections. Our intent is to use current health-based information to support water system operator's efforts in providing safe and reliable drinking water.

The Board adopted proposed changes to WAC 246-290-315 and WAC 246-290-71006 on December 15, 2025. The adopted changes align the SALs with the MCLs while keeping current protections related to PFAS in place until new federal regulations are effective.

State Action Levels, MCLs, and Trigger Levels

There are multiple PFAS rule stages, progressing to the MCLs becoming effective in April 2029. We describe these in the table below. Effective January 15, 2026, SAL values were aligned with the federal MCLs. Exceeding the original SAL was based on confirmed detection. With the rule change, exceeding a SAL is now based on the running annual average (RAA) exceeding the SAL. We will use the trigger levels shown below to determine monitoring requirements in 2027, after the initial monitoring period ends. Routine compliance monitoring begins April 26, 2027.

PFAS	Expired SAL* Replaced 1/15/26	SAL Effective 1/15/26	MCL Effective 4/26/29	Trigger Levels	Method to Establish Current Exceedance
PFOA	10 ppt	4.0 ppt	4.0 ppt	2.0 ppt	RAA
PFOS	15 ppt	4.0 ppt	4.0 ppt	2.0 ppt	RAA
PFHxS	65 ppt	10 ppt	4.0 ppt	2.0 ppt	RAA
PFNA	9 ppt	10 ppt	10 ppt	5.0 ppt	RAA
PFBS	345 ppt	--	--	--
HFPO-DA	--	10 ppt	10 ppt	5 ppt	RAA
Hazard Index**	--	1 unitless ratio	1 unitless ratio	0.5 unitless ratio	RAA

*For original SALs replaced on 1/15/26, exceedances were based on a confirmed detection.
**Hazard Index MCL: A calculation based on the presence of two or more of four contaminants; HFPO-DA, PFBS, PFNA, and PFHxS. Once calculated the MCL is 1 (unitless) and the trigger is 0.5 (unitless).

Monitoring in Compliance with Both SAL and MCL Rules

There is some overlap in monitoring requirements for SAL and MCL rules through April 2027. Water systems with detections may have monitoring requirements that meet both rules.

SAL Rule	MCL Rule
Water systems with detections will need to complete increased quarterly monitoring based on the percentage of the updated SALs, as described in the publication, PFAS Monitoring and Follow Up Actions 331-668 (PDF).	Water systems need to complete initial monitoring based on their water system size and source type.
After April 26, 2027, monitoring associated with the SALs will only apply to TNC water systems identified to be at risk to PFAS contamination.	Starting on April 26, 2027, all monitoring for community and NTNC water systems will be according to the federal compliance monitoring requirements.
Water systems that treat to remove a contaminant with a SAL are required to monitor quarterly.	Water systems that install treatment to remove PFAS with an MCL are required to monitor monthly, once the MCL is effective.

Systems must sample all sources after all treatment but prior to the distribution system. This is sometimes called the entry point to the distribution system. If a system regularly blends, a blended sample may be appropriate. All samples must be analyzed by EPA Method 537.1 or 533 by a lab accredited for PFAS in drinking water in Washington State (331-700, PDF). This list of accredited labs is also available in Marshallese, Russian, Spanish, Ukrainian, and Vietnamese.

Federal Initial Monitoring Requirements for PFAS

The federal PFAS rule requires community and NTNC water systems complete initial monitoring requirements before April 26, 2027. The initial monitoring requirements are based upon system size and source water type as shown in the table below.

All PWS Serving More than 10,000 People, No Matter the Source Type	Surface Water or GWI Sources for All Systems, No Matter the Population	All Groundwater sources for Systems Serving 10,000 or Less People
collect four quarterly samples within a 12-month period.	Collect four quarterly samples within a 12-month period.	Collect two samples within a 12-month period.
Samples in each quarter must be collected two to four months apart.	Samples in each quarter must be collected two to four months apart.	Samples must be collected five to seven months apart.

Systems may use previously collected data to satisfy some or all of the initial monitoring requirements. This includes data collected to satisfy our state rule or UCMR 5. When you use prior results to meet the initial monitoring requirements, the seasonal variation for samples is considered without regard to the year.

To meet the initial requirements, data must be received by us before April 26, 2027. Samples collected on the due date but not received may result in increased monitoring. A common mistake we notice is that samples are collected too close together. Just remember, if you sampled in February, April is two months apart.

Federal Compliance Monitoring Requirements for PFAS

Initial monitoring results are used to determine compliance monitoring that starts on April 26, 2027. A source may only qualify to move directly to reduced monitoring at the beginning of the “compliance monitoring” if they meet the following criteria.

The correct number of initial samples with the correct spacing for the system’s population and source type are met.
All samples used to meet initial monitoring are reported with results less than the trigger levels. This includes both detected and non-detect results. If a water system used UCMR 5 samples reported at less than 4.0 ppt, but collected additional replacement samples, the non-detect UCMR 5 results will not impact a source qualifying for reduced monitoring.

The following criteria will result in quarterly monitoring starting on April 26, 2027.

Initial sampling not completed appropriately.
- Too few samples based on system population or source type.
- Enough samples collected but not within the appropriate time frames (with the exception of approved seasonal sources, per Department approval).
Samples used for initial monitoring are reported as non-detect at reporting levels greater than the trigger.
Any sample had a detection equal to or above the trigger level for an analyte with a MCL.

The first compliance period will start on April 26, 2027. Because this date is in the middle of a two different compliance periods, the first compliance periods will be:

Quarterly. 4/26/27 – 6/30/27
Three years. 4/26/27 – 12/31/28

EPA released several quick reference guides and a significant figure fact sheet for the PFAS rule that you may find helpful.

Federal rules will require community and NTNC public water systems to mitigate PFAS to ensure all results are below the new MCLs by 2029. Any water system serving water with a running annual average above the MCL as of the effective date will be required to provide public notification for MCL violations. Running annual averages will be calculated on the effective date of the MCL using data collected in the quarters prior to the effective date. If you have questions regarding PFAS mitigation, please contact engineer assigned to your county.

Systems Required to Sample as Part of EPA’s Fifth Round of the Unregulated Contaminant Monitoring Rule

Water systems required to participate in EPA’s fifth round of the Unregulated Contaminant Monitoring Rule (UCMR5) received an email March 14, 2024, on how to submit their UCMR5 data if you want to use it to also meet our State PFAS requirements. UCMR5 labs are not required to report for you - you may need to provide those results to us. Whether reported by the water system or the lab, the results must be on one of our state reporting forms.

To qualify for reduced monitoring, your PFOA and PFOS results must be reported to less than 2.0 ng/L (ppt). In November 2024, EPA sent UCMR5 systems a memo about PFAS reporting for the new drinking water regulation. Systems may need to contact their lab to request the lab re-report the original data to the lower reporting limits.

If you would like to submit your reanalyzed UCMR 5 data for compliance, you can either:

Work with the lab you used for UCMR5 and have them complete the UCMR5 reporting template, or
Complete the template yourself and submit it to us with the UCMR5 sample report that you received from the laboratory.

If you use the UCMR 5 data you received from the laboratory or pulled from EPA’s database (CDX), it is very important that all system and source information at the top of the form is completed accurately and is legible. If the field for “Lab Number/Sample Number” use 999 (pre-filled on the template) for the lab number and use 00001 for the sample number. If there is more than one sample for a water system on the same day, use sequential sample numbers (such as 00001, 00002, etc.). In the “UCMR 5 Lab Information” section, please include all the lab information requested. Don’t forget to check that the units used by the lab are the same as the units on the template. You may need to convert the data to the correct units.

Once you have completed the report, you can email a scanned copy along with the original laboratory report to ODWdataentry@doh.wa.gov.

Free PFAS Analysis Offered to meet Initial Sampling

We have a free PFAS sampling program for Community and NTNC systems to help water systems meet initial federal PFAS requirements. We will schedule samples in 2026, in consideration of any existing data so that the combination of results satisfies initial federal PFAS requirements.

For water systems not currently signed up to participate in this free PFAS sampling program, you can still sign up by submitting you information via our online PFAS Free Sampling Enrollment Form.

Systems with detections must collect follow-up samples and comply with the rule requirements.

Funding is limited and we may prioritize systems based on risk if volunteers exceed available funding.

Monitoring and Public Notification Changes with updated SALs

On January 15, the Board aligned the SALs with the MCLs. Some sources may see changes in their monitoring based on the percentages of their prior results compared to the updated SALs. Since the new SALs are aligned with the MCLs, PFAS SAL exceedances are now based on exceeding a running annual average (RAA). There is no longer a SAL for PFBS with these changes. PFBS is assessed with the hazard index SAL. All data collected after January 14, 2026, will be used to calculate the RAAs.

For public water systems with PFAS detections, PFAS Monitoring and Follow Up Actions 331-668 (PDF) outlines the monitoring requirements in the revised WAC 246-290.

Exceeding a SAL for PFAS

Systems with a PFAS running annual average above a SAL must provide public notification to their customers within 30 days of notification of the exceedance. The Word templates below have all the required elements for public notification. We made it editable, so that you may include specific details about your water system.

Public Notice PFAS Detection 331-683 (Word). It is also available in Russian, Spanish, Tagalog, Ukrainian, and Vietnamese.

PFAS Results in Your Consumer Confidence Report

Community water systems that have any detected level of PFAS in the water supply must report the PFAS results on their consumer confidence report, as required in the Washington Administrative Code. All PFAS detections must be included in your data table. We recommend water systems inform customers of their results compared to the MCLs for transparency, but you must include the SALs at a minimum until 2027 when you must present the data compared to the MCLs.

PFAS Monitoring for Transient Non-Community (TNC) Systems

Transient non-community (TNCs) systems may be required to monitor if their source of supply is near a known PFAS contaminated site. We will notify affected TNCs when more information is known. If you’re required by us to sample for PFAS as a TNC system due to associated risk, you are eligible for free-PFAS testing, as explained in our publication, Emerging Contaminants in Small and Disadvantaged Communities Grant Guidelines 331-765 (PDF).

We will use the following criteria to determine TNCs that may be at risk to PFAS.

Within one mile of a fire station or fire training facility.
Within one mile of a landfill.
Within one mile of a wastewater treatment plant outfall or large on-site sewage system drain field.
Within one mile of a public water system (PWS) source with a known PFAS detection.
Within two miles of a United States Department of Defense site.
Within two miles of an airport.

Mapping PFAS Data: Water System PFAS Results on the PFAS Dashboard

We share all required PFAS results on our PFAS dashboard. Public water systems must test all active, permanent, and seasonal sources of their water supply.

You can view the PFAS data as a general map showing detections, a table with detailed data, or as a summary using the tabs in the header. Click on a dot on the map to see information about the specific water system source. You can sort using the criteria to the left of the map or sort data on the table tab. The dashboard summary includes PFAS testing statistics. You can download the entire PFAS data set to sort in Excel from below the Dashboard.

If you would like to share your mitigation plans on our PFAS Dashboard, please send a brief one sentence description to your source monitoring contact and the engineer assigned to your county.

Funding for PFAS Mitigation and Source Water Protection

The federal Bipartisan Infrastructure Law makes additional funding available in grants and loans to public water systems for PFAS treatment, new source, or another preferred option for mitigating PFAS contamination. If interested, email dwsrf@doh.wa.gov or contact the engineer assigned to your county. Visit our Drinking Water State Revolving Fund webpage to learn more about funding options.

The Source Water Protection (SWP) grant program provides financial assistance to support drinking water protection projects that reduce the risk of contamination within a source water protection area. If interested, contact chelsea.cannard@doh.wa.gov or t the engineer assigned to your county. Visit our SWP Local Assistance Grant Program webpage to learn more about funding options.

Additional Information

For over-all information on PFAS, visit our general PFAS Contaminant webpage. Information is also available in our PFAS Frequently Asked Questions 331-681 (PDF), which may be useful for water systems in communicating with their customers. It's also available in Russian, Spanish, Tagalog, Ukrainian, and Vietnamese.

For questions about monitoring and notification requirements, please contact the source monitoring staff for your county.

You can also find source monitoring contacts on your Water Quality Monitoring Schedule (WQMS) or on our Drinking Water Contacts webpage.

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