PFAS and Forever Chemicals in San Antonio Water 2026: EPA Rules, SAWS Data, and Private Well Guidance

What are PFAS and why are they called forever chemicals?

PFAS are a class of more than 12,000 synthetic compounds that share a carbon-fluorine bond, one of the strongest in organic chemistry. That bond is why they do not break down in the environment or in the human body over any practical timescale. They were developed beginning in the 1940s and found commercial use in nonstick cookware coatings, stain-resistant fabric treatments, food packaging, and firefighting foam known as aqueous film-forming foam (AFFF). Industrial manufacturers released PFAS into air and water for decades before the environmental and health consequences were documented.

Long-term exposure above health benchmarks has been associated with increased risk of certain cancers (kidney and testicular), thyroid disruption, immune system effects, and elevated cholesterol, according to the National Cancer Institute and EPA toxicity assessments referenced in the April 2024 final rule. The health benchmarks do not imply that any exposure below those levels is without risk: the EPA set the maximum contaminant level goal (MCLG) for PFOA and PFOS at zero, meaning the agency concluded there is no known safe level. The MCL of 4 ppt for each reflects the lowest level that can currently be reliably measured and enforced at scale.

The six PFAS compounds regulated in the 2024 rule are PFOA, PFOS, PFNA, PFHxS, GenX (also called PFPO-DA), and PFBS. PFOA and PFOS are the two most widely studied and were the dominant compounds in firefighting foam and many industrial applications through the early 2000s. PFNA, PFHxS, and GenX are shorter-chain variants that manufacturers shifted to as PFOA and PFOS were phased out, only to find that these compounds also persist in the environment and carry their own toxicity profiles. The EPA PFAS page at epa.gov/sdwa/and-polyfluoroalkyl-substances-pfas carries the complete rule text, fact sheets, and compliance guidance for public systems.

What does the April 2024 EPA PFAS drinking water rule require?

On April 10, 2024, the EPA announced the National Primary Drinking Water Regulation for PFAS, the first enforceable federal limits on any PFAS compounds in drinking water. The rule covers public community water systems only, meaning systems that serve at least 25 people or 15 service connections year-round. Private wells are explicitly outside the scope.

The MCLs established by the rule, as of the April 26, 2024 Federal Register publication, are:

• PFOA: 4.0 parts per trillion (ppt) individually
• PFOS: 4.0 ppt individually
• PFNA: 10 ppt individually
• PFHxS: 10 ppt individually
• GenX (PFPO-DA): 10 ppt individually
• PFBS: regulated through a combined hazard index with PFNA, PFHxS, and GenX

Public water systems had five years from the publication date to come into compliance. The EPA in May 2025 announced it would keep the PFOA and PFOS MCLs at 4 ppt while proposing a two-year compliance extension and reviewing the MCLs for the other four compounds. Verify the current status at epa.gov/sdwa, as the regulatory timeline continues to evolve.

Nearly 50 Texas public water systems reported PFAS detections, with some exceeding the new MCLs, according to the Texas Tribune (April 16, 2024). The Texas Commission on Environmental Quality (TCEQ) is coordinating initial compliance monitoring for Texas public water systems beginning in 2027. Current TCEQ PFAS guidance is published at tceq.texas.gov/drinkingwater/chemicals/pfas.

What did SAWS find in its PFAS testing?

San Antonio Water System was included in the EPA's mandatory Unregulated Contaminant Monitoring Rule 5 (UCMR5) testing program, which required large public water systems to test for 29 PFAS compounds between 2023 and 2025 and report results to the EPA. SAWS delivers water to roughly 500,000 customers across the San Antonio metro area.

In April 2024, reporting by the San Antonio Report (April 23, 2024) and Axios San Antonio (April 25, 2024) confirmed that a SAWS well in Castle Hills tested positive for PFAS, specifically PFOS. SAWS staff reported the detection remained below the new federal MCL of 4 ppt. SAWS's communication at the time stated that the system was not in violation of any rule and that staff were not concerned about the levels found.

The SAWS annual water quality report, which covers testing conducted in the prior calendar year, is the authoritative public record for SAWS PFAS monitoring results. The 2025 report covering 2024 data and the 2026 report covering 2025 data are both available at saws.org/your-water/water-quality/water-quality-report. Verify directly with SAWS for current PFAS figures before making any health or treatment decisions.

PFAS monitoring summary: San Antonio area public sources (2023 to 2026)

Data compiled from publicly cited sources as of August 2026. Verify all figures with the primary sources listed before making treatment or health decisions. Private well results are not included in any public registry.

Do private wells in San Antonio need PFAS testing?

Private wells are not covered by the Safe Drinking Water Act and are not subject to any federal or Texas state PFAS monitoring requirement. The Texas Groundwater Protection Committee confirms that for domestic well owners, there are no state or federal requirements for monitoring drinking water quality as there are for public water supply systems (tgpc.texas.gov/water-wells/private-wells). The responsibility for testing and treatment rests entirely with the well owner.

The EPA recommends voluntary PFAS testing for private wells when the property is:

• Near a military installation or former military base that used AFFF firefighting foam (Joint Base San Antonio Randolph and Lackland are both in the San Antonio metro area)
• Near an industrial facility that manufactured or used PFAS-containing products
• Near an airport where AFFF was used for fire suppression training
• On or near land where municipal biosolids were historically applied as agricultural fertilizer
• Near a location with a documented PFAS groundwater plume

Joint Base San Antonio (JBSA) includes Randolph, Lackland, and Fort Sam Houston. Military installations with active or historical AFFF use have been identified as PFAS contamination sources nationally. Private well owners within a few miles of these installations should consider voluntary PFAS testing regardless of whether they have noticed any change in their water.

A specialty PFAS panel in Texas runs approximately $150 and must be specifically requested from a certified laboratory. It is not included in standard well panels for bacteria, nitrates, or hardness. For guidance on which labs are certified for PFAS testing in Texas, contact the TCEQ laboratory accreditation program at tceq.texas.gov.

PFAS and the Edwards Aquifer: what northern-tier San Antonio well owners should know

The Edwards Aquifer is a karst limestone formation spanning approximately 3,000 square miles beneath central Texas. Its geology does not naturally produce PFAS. PFAS enter the Edwards Aquifer only through contamination from the surface: AFFF from military or airport fire training, industrial discharge, or biosolids applied to land in the recharge zone.

The Edwards Aquifer Authority monitors aquifer water quality through its own program and publishes data at edwardsaquifer.org. The dominant water quality concerns from Edwards Aquifer wells are not PFAS but hardness from limestone dissolution (typically 15 to 25-plus grains per gallon), occasional elevated combined radium in certain zones of Kendall County, and iron or hydrogen sulfide from the Trinity Aquifer in deeper Hill Country wells.

The Castle Hills detection from a SAWS well illustrates that PFAS can reach municipal groundwater in the San Antonio area from localized surface sources. Private well owners in the northern San Antonio suburbs, including Helotes, Leon Valley, and Castle Hills, whose wells draw from the Edwards or Trinity Aquifer and who are near any of the identified risk factors listed above, should arrange voluntary PFAS testing. This is a precautionary step, not a response to a documented widespread well contamination event in those areas as of the time of this publication.

For the full picture of Edwards Aquifer water quality relevant to Hill Country communities, read our guide on US well water quality by state and aquifer. For Boerne and Kendall County, see our Boerne, TX water quality 2026 guide.

How do you remove PFAS from drinking water?

The EPA identifies two primary treatment technologies for PFAS reduction in drinking water at the residential scale: reverse osmosis (RO) and high-capacity granular activated carbon (GAC). Both are referenced in the EPA's PFAS treatment guidance at epa.gov/sdwa.

Reverse osmosis uses a semi-permeable membrane to physically block PFAS molecules from passing through with the treated water. Under-sink RO systems are the most practical residential option. A properly maintained membrane with timely filter replacement can reduce PFOA, PFOS, and the other regulated PFAS compounds significantly at the drinking tap. RO systems treat the water at the point of use: the kitchen faucet and any connected outlets. They do not treat bathing or laundry water, but ingestion from drinking and cooking represents the primary exposure pathway for PFAS in drinking water.

Granular activated carbon adsorbs PFAS onto the carbon surface as water passes through a bed of the media. GAC is more practical at the whole-system or municipal scale because the large contact times and media volumes needed for effective PFAS adsorption are difficult to achieve in a compact under-sink unit. GAC is effective for longer-chain PFAS like PFOA and PFOS; shorter-chain variants like GenX and PFBS adsorb less efficiently and may pass through carbon more readily. For residential point-of-use applications, RO outperforms GAC for the full spectrum of regulated PFAS.

Pitcher and refrigerator filters with standard activated carbon provide inconsistent and often minimal PFAS reduction and are not a reliable substitute for RO. The specific performance depends on the carbon type, contact time, and flow rate, and most standard pitcher filters are not certified to NSF/ANSI 58 or 62 for PFAS reduction.

For most San Antonio area homeowners on city water, SAWS is meeting federal limits, but an under-sink RO system provides an additional layer of protection for drinking water at the tap and simultaneously reduces other regulated contaminants including nitrate, radium, and total dissolved solids. For well owners with a confirmed PFAS detection, RO at the drinking tap is the standard first response while you assess whether additional whole-house treatment or source remediation is needed.

Read our comparison of reverse osmosis versus whole-house filtration for more detail. For a broader look at what else San Antonio water contains, see our guide to PFAS in San Antonio water: 2026 test results.