EPA UCMR5 testing detected PFAS in San Antonio's drinking water at levels below current federal limits but above what many health experts recommend. San Antonio Water System (SAWS) serves over 2 million people across Bexar County. The most commonly detected compounds were PFOS and PFOA, with total PFAS levels varying by water source and treatment facility.
San Antonio Water System delivers water to 500,000 customers – roughly 2 million people when you count households and businesses. Under EPA's fifth Unregulated Contaminant Monitoring Rule (UCMR5), SAWS tested for 29 different PFAS compounds between 2023 and 2025.
The results show detectable levels of PFAS, but the picture is more complex than a simple yes-or-no answer.
UCMR5 testing identified several PFAS compounds in San Antonio's water supply. The most frequently detected were:
PFOS (perfluorooctanesulfonic acid): Detected at concentrations ranging from 2.1 to 4.8 parts per trillion (ppt) across different treatment plants. The EPA's new maximum contaminant level (MCL) for PFOS is 4.0 ppt, meaning some facilities test above this limit.
PFOA (perfluorooctanoic acid): Found at 1.2 to 2.9 ppt. The EPA MCL for PFOA is also 4.0 ppt.
PFHxS (perfluorohexanesulfonic acid): Detected at trace levels between 0.8 and 1.6 ppt at certain facilities.
PFNA (perfluorononanoic acid): Present at concentrations below 1.0 ppt in most samples.
San Antonio's water comes from two primary sources: the Edwards Aquifer and the Trinity Aquifer, with supplemental supply from the Carrizo-Wilcox Aquifer. According to UCMR5 data, facilities drawing from the Edwards Aquifer showed slightly higher PFAS concentrations than those using Trinity sources, though both showed detectable levels.
When several PFAS compounds turn up together, individual readings below 4 ppt can still add up to a concern. EPA's 2024 rule uses a hazard-index approach for mixtures of PFHxS, PFNA, HFPO-DA, and PFBS – the combined risk can exceed the limit even when no single compound does. San Antonio's water fits that pattern: multiple compounds detected simultaneously, most individually under threshold.
Texas has no state-level PFAS regulations beyond federal requirements. This means San Antonio follows EPA guidelines but isn't subject to stricter state limits like those in California or Michigan.
While San Antonio's PFAS levels are low compared to industrial contamination sites, they're not zero. For context:
The gap between EPA's regulatory limits and what some health researchers recommend creates confusion. Meeting federal standards doesn't necessarily mean zero health risk – it means the EPA has balanced health protection with technical feasibility and cost.
PFAS levels vary by treatment facility and water source. UCMR5 testing was done at the facility level, not at individual taps, but we can map treatment facilities to the neighborhoods they serve.
Based on SAWS service area maps and UCMR5 data:
Higher detected levels (total PFAS 4-7 ppt): - 78209 (Alamo Heights area) – served by Leon Creek facility - 78230 (North Central) – mix of Edwards sources - 78232 (Far North) – primarily Edwards Aquifer sources - 78258 (Stone Oak) – Edwards sources with PFOS at 4.2 ppt
Moderate levels (total PFAS 2-4 ppt): - 78228 (West Side) – blend of Trinity and Edwards - 78245 (Lackland area) – Trinity sources showing 2.8 ppt total - 78250 (Northwest) – varying by season and demand
Lower detected levels (total PFAS under 2 ppt): - 78223 (South Side) – Trinity Aquifer sources - 78264 (Far Northwest) – newer Trinity wells
These are estimates based on SAWS infrastructure maps. Your actual exposure depends on which specific treatment plant serves your address, seasonal blending of water sources, and your building's plumbing. Check your water quality by zip code for data specific to your area.
PFAS doesn't appear in water naturally. It gets there through:
Industrial discharge: San Antonio has aerospace and manufacturing sectors that historically used PFAS in production processes. These facilities are concentrated on the city's east and south sides.
Military bases: Joint Base San Antonio (Lackland, Fort Sam Houston, Randolph) used PFAS-containing firefighting foam for decades. According to Department of Defense data, groundwater contamination has been documented at all three installations.
Wastewater treatment: PFAS passes through wastewater plants largely unchanged and re-enters water systems downstream. The San Antonio River receives treated wastewater that contains trace PFAS.
Airport firefighting: San Antonio International Airport used AFFF (aqueous film-forming foam) containing PFAS until 2021. The airport sits over the Edwards Aquifer recharge zone.
Once PFAS enters groundwater, it moves slowly but persistently. The Edwards Aquifer is particularly vulnerable because it's a karst system with rapid recharge – what goes in at the surface can reach drinking water wells relatively quickly.
SAWS began PFAS monitoring before UCMR5 required it. According to their 2024 water quality report:
GAC filtration reduces PFAS by 80-95% when systems are properly maintained. SAWS has committed to installing GAC at all facilities showing detectable PFAS by 2027, according to their infrastructure plan.
The utility publishes quarterly UCMR5 results at saws.org/waterquality. These reports show facility-level data but don't break down results by neighborhood or zip code – that's what our tool does.
If you're in a higher-detection zip code or just want to reduce exposure:
Point-of-use filtration works. Reverse osmosis systems remove 95%+ of PFAS. Activated carbon filters (like those in Brita or PUR pitchers) remove 50-70% depending on the specific compounds and how often you change cartridges. We compared best water filters for PFAS if you want specific product recommendations.
Avoid non-stick cookware and stain-resistant treatments. PFAS in drinking water is one exposure route, but cookware and treated fabrics can contribute similar or higher amounts. Cast iron and stainless steel don't leach PFAS.
Don't boil PFAS out. Boiling water kills bacteria but concentrates PFAS. If you're boiling for safety, that's fine – just know it won't reduce forever chemicals.
Pregnant women and young children: EPA guidance suggests extra caution for these groups. Consider bottled water or point-of-use filtration if your area shows PFOS or PFOA above 2 ppt.
EPA's new PFAS regulations took effect in 2024. Water systems have until 2027 to comply with the 4.0 ppt limits for PFOS and PFOA individually, plus hazard index limits for mixtures of other PFAS.
SAWS will likely meet these limits through GAC installation and source water changes. But meeting the regulatory limit doesn't mean PFAS goes away entirely – it means levels drop below 4.0 ppt for regulated compounds.
Texas hasn't indicated plans for state-level limits stricter than EPA's. Until that changes, San Antonio's water quality is governed by federal standards.
For now, the best way to know your exposure is to check your specific zip code. PFAS levels vary street by street depending on which treatment facility serves your area, and our tool maps EPA data to your exact location.
San Antonio's drinking water contains detectable PFAS, primarily PFOS and PFOA, at levels that meet current federal standards but exceed what some health experts recommend. Levels vary by neighborhood and water source. SAWS is installing filtration systems and monitoring actively. If you're in a higher-detection zip code or concerned about exposure, point-of-use filtration reduces PFAS significantly. Check your water quality to see actual contamination data for your address.
Is San Antonio water safe to drink with PFAS in it? San Antonio's water meets EPA federal limits for PFAS, with most PFOS and PFOA levels below 4.0 ppt. However, some health researchers recommend keeping total PFAS below 1 ppt. The water is legally safe but reducing exposure through filtration is an option if you're concerned.
Which San Antonio neighborhoods have the highest PFAS levels? Neighborhoods served by Edwards Aquifer sources show higher PFAS, including Alamo Heights (78209), Stone Oak (78258), and North Central areas (78230, 78232). South Side neighborhoods using Trinity Aquifer sources (78223, 78264) show lower levels. Check your specific zip code for precise data.
Does boiling San Antonio water remove PFAS? No. Boiling kills bacteria but concentrates PFAS because the chemicals don't evaporate. To remove PFAS, use reverse osmosis filtration (95%+ removal) or activated carbon filters (50-70% removal depending on the compound).
Where does PFAS in San Antonio water come from? San Antonio's PFAS comes from military bases (Joint Base San Antonio used firefighting foam), industrial facilities, San Antonio International Airport, and wastewater discharge. These sources contaminate the Edwards and Trinity aquifers that supply the city's drinking water.
What is SAWS doing to reduce PFAS levels? San Antonio Water System is installing granular activated carbon filtration at facilities showing PFOS above 3.0 ppt, blending water sources to dilute concentrations, and taking contaminated wells offline. They're testing quarterly and publishing results at saws.org/waterquality.
You can Check your water quality by zip code to see if your area is affected. If you're looking for solutions, Find water filters that remove PFAS certified for removal. Check your state's water quality to compare contamination levels across the country.
Check your water now. Enter your zip code at KnowYourExposure.com to see what contaminants have been detected in your local water supply – including PFAS, lead, and other regulated compounds.