San Antonio's tap water comes mostly from groundwater, led by the Edwards Aquifer. In EPA's UCMR5 testing, SAWS had no PFOA or PFOS detected above the reporting limit, but three short-chain PFAS showed up at low levels. A carbon block or reverse osmosis filter reduces these, plus the chlorine SAWS uses for disinfection. Most San Antonio homes care most about hard water, chlorine taste, and short-chain PFAS.
San Antonio Water System (SAWS) serves about 2 million people. The Edwards Aquifer supplied about 47% of its water in 2025. The rest came from the Carrizo, Simsboro, Trinity and Wilcox aquifers (including the Vista Ridge pipeline), brackish groundwater desalination, Canyon Lake surface water in some areas, and SAWS's H2Oaks aquifer storage and recovery (ASR) facility, which stores surplus Edwards water in the Carrizo Aquifer. In EPA's UCMR5 testing, SAWS had no PFOA, PFOS, PFHxS or PFNA detected at or above the reporting limits. Three short-chain PFAS were detected at low levels: PFBA (up to 9.2 parts per trillion), PFBS (up to 3.8 ppt) and PFPeA (3.2 ppt). SAWS's own 2026 water quality report lists only lithium in its UCMR5 table.
PFAS aren't the only concern. SAWS disinfects with free chlorine (about 1.5 ppm on average in 2025), which any carbon filter certified for chlorine reduction handles. The Edwards Aquifer also contributes naturally occurring minerals, high calcium and magnesium levels that make San Antonio water very hard (typically 15 to 20 grains per gallon, per SAWS).
The PFBA, PFBS and PFPeA detections come from KnowYourExposure's copy of EPA's UCMR5 dataset for SAWS. These are trace levels, and none of the three has its own federal limit. Short-chain PFAS like these leave the body faster than PFOA and PFOS, but they're also harder for carbon filters to catch. If you're filling baby bottles, cooking, or drinking multiple glasses a day (which you should in San Antonio's heat), filtering makes sense.
We researched filters for San Antonio's contaminant profile using each maker's certifications and published test data: PFAS removal, chlorine reduction, and ideally some hardness management. Here's what actually works.
| Filter | Price | PFAS Removal | Chlorine Reduction | San Antonio Fit | Where to Buy | |--------|-------|--------------|----------------------|-----------------|---------------| | AquaTru Countertop | $449 | Certified for PFOA/PFOS; RO also reduces short-chain PFAS | Yes | Best for PFAS + hardness: RO removes dissolved minerals that build up in carbon filters | Amazon | | Clearly Filtered Under-Sink | from ~$495 | Lab-tested >99.6% PFOA/PFOS; not certified | Yes (lab-tested) | Middle ground: no RO wastewater | Amazon | | Berkey Light (2.75 gal) | $299 | Brand-reported lab tests; not certified | Brand-reported | Gravity-fed backup during boil notices; no installation | Amazon) | | Brita Elite Pitcher | $35-45 | No current PFAS certification | Yes (NSF 42) | Budget pick; not certified for any PFAS, including the short-chain PFAS found in SAWS testing | Amazon | | APEC ROES-50 | ~$160-230 | RO (WQA-certified to NSF 58) | Yes | Best budget RO for San Antonio; reduces most dissolved contaminants but sends several gallons down the drain per gallon filtered | Amazon |
Not every tap needs the same level of filtration. Here's how we'd prioritize if you're installing filters gradually:
For most San Antonio homes, the choice is RO versus a well-documented carbon filter. The Clearly Filtered Under-Sink system is the no-wastewater option: the brand's independent lab data show more than 99.6% PFOA/PFOS reduction and strong chlorine reduction, though it isn't certified, and SAWS's detections are short-chain PFAS, which carbon catches less consistently than RO. San Antonio's drought cycles make water waste a real consideration, since older RO designs flush 3-4 gallons down the drain for every gallon filtered.
Your source blend depends on where you live and on demand: SAWS mixes Edwards water with other aquifers, stored ASR water, and Canyon Lake surface water in some areas. If you're outside SAWS's service area (Canyon Lake-area homes, for example, are served by a different utility), check your own provider's report.
For families with infants or anyone immunocompromised, step up to the AquaTru Countertop RO. It's overkill for most people, but RO removes the widest range of contaminants, including short-chain PFAS. The countertop design also means you can take it with you if you move (a real advantage in San Antonio's hot rental market).
Frankly, the Brita Elite is fine if you're on a tight budget and just want better-tasting water. But it's not sufficient if you're specifically worried about the PFAS SAWS detected. Brita's current Elite data sheet makes no PFAS claim (earlier versions listed only PFOA and PFOS), and the PFAS found in San Antonio's testing were other, short-chain compounds.
Most under-sink filters install in 30-45 minutes with basic tools. San Antonio's high mineral content means you might see white calcium buildup on fittings over time–that's normal. Use Teflon tape on threaded connections to prevent minor leaks.
If you're in an older home (pre-1980s) near downtown or Southtown, check whether your service line is lead. SAWS says it has been replacing lead pipe in the public system since the 1980s, but its inventory of about 642,000 service lines still has more than half of materials unconfirmed. Lead + PFAS is a double exposure you don't want. A mail-in lab lead test is more reliable than hardware-store strips, which usually only flag lead near 15 ppb. If lead shows up, you need a filter that handles both: RO systems and carbon blocks certified to NSF/ANSI 53 for lead do, but basic carbon doesn't.
Whole-house systems for San Antonio homes typically cost $1,200-$3,000 installed. They're worth it if you're filtering chlorine for skin and hair or if multiple people in the house drink a lot of water. But for PFAS specifically, the under-sink or countertop route covers your primary exposure at a fraction of the cost.
We're not sure how much PFAS variability exists across SAWS's distribution zones. The UCMR5 testing sampled specific entry points and treatment plants, but San Antonio's system blends several sources depending on demand and season. Your specific neighborhood might see different levels than the citywide average. SAWS doesn't publish zone-level PFAS data yet (most utilities don't), so we're working with system-wide numbers.
Another uncertainty: the EPA's 2024 PFAS rule set limits for six compounds, but the three detected in SAWS's UCMR5 samples (PFBA, PFBS and PFPeA) don't have individual federal limits; PFBS counts only toward a mixture hazard index that EPA proposed rescinding in May 2026. The health research on these is thinner. Some toxicologists think they're less harmful because they clear the body faster. Others point out we just don't have 20-year studies yet. Take it with a grain of salt, but we'd filter them out if the technology exists–which it does.
If you're moving from Dallas, San Antonio's water is cleaner on PFOA and PFOS: Dallas's 2023 UCMR5 samples included single PFOA readings up to 6.3 ppt, while SAWS had none detected. Houston's main system, like San Antonio's, showed short-chain PFAS but no PFOA or PFOS at the reporting limit. San Antonio benefits from the Edwards Aquifer's natural limestone filtration, which is why SAWS's treatment process is simpler.
But San Antonio's hard water is harder than almost anywhere in Texas. That calcium buildup clogs filters faster and fouls RO membranes sooner than in softer-water cities like Austin (which uses the Highland Lakes, a softer source). Expect to replace carbon filters every 4-6 months instead of the 6-12 months advertised on the box. RO membranes rated for 2 years might last 18 months in San Antonio. Budget for that.
Carbon block and Affinity filters: every 6 months in San Antonio (not the 12 months some brands claim). The hard water accelerates clogging. If your water pressure drops noticeably or you taste chlorine again, the filter is spent.
RO membranes: every 18-24 months. You'll know it's time when the waste water ratio increases (you're flushing 5-6 gallons per filtered gallon instead of 3) or when TDS (total dissolved solids) starts creeping up. A $15 TDS meter from Amazon is worth having–test your filtered water every few months. It should read under 20 ppm. If it's climbing toward 50+, the membrane is failing.
Pitcher filters (Brita, PUR): follow the rated capacity, and replace sooner if flow slows. San Antonio's mineral load can clog the small filter bed early.
The EPA's 2024 PFAS rule gives water systems until 2029 to comply with the new limits (in May 2026 EPA proposed letting some request until 2031), and SAWS's PFOA and PFOS results are already below them. That's good news. The bad news: compliance doesn't mean zero PFAS, and EPA's health goal for PFOA and PFOS is zero. If you're pregnant, feeding an infant, or just prefer the precautionary route, home filtration closes the gap.
San Antonio's population is growing, and SAWS now serves about 2 million people. The Edwards Aquifer is a finite resource; the H2Oaks ASR facility held about 155,000 acre-feet as of 2024, per the Texas Water Development Board. As the city grows, SAWS is leaning more on other sources, such as imported groundwater and brackish desalination. A filter you install now will keep working regardless of how the city's water strategy evolves.
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Check PFAS contamination data by ZIP code to see how your specific San Antonio neighborhood tests. SAWS's system-wide numbers are averages–your local levels might differ. Our guide to PFAS explains the health research behind the EPA's 2024 rule, and the water filter comparison page breaks down which technologies remove which contaminants. For a deeper dive into everything SAWS tests for beyond PFAS, see the full list of regulated drinking water contaminants.
Does San Antonio water have PFAS? At low levels. In EPA's UCMR5 testing, SAWS had no PFOA, PFOS, PFHxS or PFNA detected at the reporting limits, but three short-chain PFAS were: PFBA (up to 9.2 parts per trillion), PFBS (up to 3.8 ppt) and PFPeA (3.2 ppt).
What is the best water filter for San Antonio tap water? The Clearly Filtered Under-Sink system is the no-wastewater option: the brand's independent lab data show more than 99.6% PFOA/PFOS reduction and strong chlorine reduction, though it isn't certified. For the short-chain PFAS SAWS detected, families with infants, or maximum filtration, the AquaTru Countertop RO system is worth the upgrade.
Why does San Antonio water taste different than other cities? Mostly minerals. SAWS's groundwater sources, led by the Edwards Aquifer, carry a lot of dissolved calcium and magnesium (typically 15 to 20 grains per gallon of hardness), which gives the water a distinct mineral taste. SAWS disinfects with chlorine, which a basic carbon filter removes.
Do I need a whole-house filter in San Antonio? Not for PFAS–under-sink or countertop filtration at your drinking water tap covers most exposure. Whole-house filters make sense if you want chlorine removal for skin and hair (especially if you have eczema or dry scalp) or if you have lead service lines. Expect to pay $1,200-$3,000 installed for a whole-house system rated for San Antonio's hard water.
How often should I replace my water filter in San Antonio? Every 6 months for carbon block or Affinity filters–faster than the 12 months some brands advertise, because San Antonio's hard water clogs filters quicker. RO membranes last 18-24 months (not the 2+ years rated for softer water). Replace pitcher filters every 2 months if using daily. Test your filtered water with a TDS meter ($15) to catch membrane failure early.