Latest Testing Results (2024 Data)

• Lead & Copper: The 2024 testing period showed a 90th percentile lead level of just 1.6 ppb — a marked improvement on the previously reported 3.25 ppb and well below the EPA action level of 15 ppb. Zero sites exceeded the action level. Copper was at 0.187 ppm, also well below its 1.3 ppm limit. SAWS’s Project Lead programme offers free service line inspections for homes built before 1989 to help complete the public inventory — visit saws.org/lead.
• PFAS (UCMR5, 2024): UCMR5 monitoring detected PFBS (Perfluorobutanesulfonic acid) at an average of 0.0038 ppb (3.8 ppt) — at the minimum reporting level and below the EPA’s 4 ppt MCL. Multiple other PFAS were not detected. This is one of the most favourable PFAS profiles of any large US city, reflecting the protected nature of the Edwards Aquifer system. For PFAS context see our water quality testing guide.
• Regulatory Compliance: The SAWS main system received no violations in 2024. Bacteria monitoring across 390 sites found one E. coli positive out of thousands of samples — no MCL violation was triggered. Turbidity peaked at 0.08 NTU, well within the 1 NTU limit, with 100% of monthly samples meeting the 0.3 NTU treatment technique requirement.

Multi-Aquifer Excellence

• Edwards Aquifer (Primary Source): The Edwards Aquifer, supplying the majority of SAWS’s water, is one of the most productive aquifer systems in the world. Water is naturally filtered through limestone over thousands of years, removing contaminants and providing excellent baseline quality. Strict recharge zone regulations and a comprehensive watershed management programme protect long-term quality.
• Carrizo-Wilcox Aquifer System: The Carrizo, Simsboro, and Wilcox aquifers provide supplementary groundwater supply, particularly important as Edwards Aquifer levels respond to seasonal recharge. These deeper aquifers provide additional supply resilience during drought years.
• Surface Water & Purchased Supply: Canyon Lake surface water and purchased supplies from regional authorities (Canyon Regional Water Authority, GBRA Western Canyon, Vista Ridge LLC, Schertz-Seguin Local Government Corporation, and others) supplement aquifer supply during peak demand. Surface water sources show higher TTHMs — Vista Ridge supply showed TTHMs of 47 ppb in 2024 compared to 33 ppb for the main system.

Disinfection Byproducts: The Primary EWG Concern

• Total Trihalomethanes (TTHMs): Averaged 22.9 ppb in the main system (range 0–52.9 ppb) — within the EPA legal limit of 80 ppb but 152x above EWG’s health guideline of 0.15 ppb. San Antonio’s aquifer water is naturally higher in bromide than many systems, leading to elevated formation of brominated disinfection byproducts (bromoform at 2.95 ppb, dibromochloromethane at 5.55 ppb) when chlorinated.
• Haloacetic Acids (HAA5s & HAA9s): HAA5s averaged 5.76 ppb (58x EWG guideline; legal limit 60 ppb); HAA9s at 9.67 ppb (161x EWG guideline). Key components include dibromoacetic acid (2.41 ppb, 80x EWG) and bromochloroacetic acid (2.12 ppb, 106x EWG) — both elevated due to the naturally high bromide content of the source water.
• Why This Occurs: Bromide occurs naturally in the Edwards Aquifer geology. When chlorine is used to disinfect, it reacts with bromide to form brominated disinfection byproducts at higher rates than in typical surface water systems. SAWS levels remain within all EPA limits but are higher relative to EWG’s stricter health-based benchmarks.

Water Sustainability Leadership & Infrastructure

• World-Class Recycled Water System: SAWS operates one of the largest direct recycled water systems in the world, producing over 50 million gallons daily of ultra-pure recycled water through advanced membrane bioreactor and reverse osmosis technology. This helps preserve pristine aquifer water for drinking while meeting non-potable demand.
• Vision2040 Water Plan: SAWS’s long-term sustainability plan aims to achieve water neutrality — meaning all future growth will be supplied through recycled water, conservation, and alternative supplies without increasing raw aquifer withdrawals. Per capita water use has fallen by over 40% since 1990.
• Smart Infrastructure: SAWS has deployed over 600,000 smart meters with real-time leak detection. Despite this, the 2024 water loss audit reported a combined total of approximately 19.2 billion gallons lost system-wide through main breaks, leaks, metering inaccuracies, and other causes — an ongoing challenge for a large, ageing distribution network.
• Project Lead: SAWS is actively building its lead service line inventory as required under the EPA’s updated Lead and Copper Rule. Free inspections are available for eligible customers (homes built before 1989 with unknown service line material) — this is a proactive step that distinguishes SAWS from many peer utilities. For independent testing options see our water quality testing guide.

Radioactive Contaminants: A Natural Aquifer Characteristic

San Antonio’s aquifer-sourced water naturally contains low levels of radioactive minerals from geological deposits. Combined radium 226/228 was detected at 1.82 pCi/L — below the EPA legal limit of 5 pCi/L but 6.8x above EWG’s health guideline of 0.05 pCi/L. Uranium was detected at 1.7 µg/L (well below the 30 µg/L legal limit). Beta/photon emitters at 5.5 pCi/L remain well below the EPA’s concern level of 50 pCi/L. These levels are characteristic of limestone aquifer systems and are not a regulatory concern, though EWG’s more stringent guidelines flag them. For broader context on Texas water quality compare with our Texas state overview and nearby cities including Austin, Houston, and Dallas. If you’re weighing filtration options, our water filter solutions page includes recommendations for San Antonio’s contaminant profile.