Austin TX metro: water quality. Austin draws its water from the Colorado River of Texas (not the more famous Colorado River out west), specifically from
Austin draws its water from the Colorado River of Texas (not the more famous Colorado River out west), specifically from Lake Austin and Lake Travis in the Highland Lakes system. Austin Water serves about 1 million customers across the city and extraterritorial jurisdiction. San Antonio, on the southern end of this metro, relies on the Edwards Aquifer – a massive karst limestone formation that supplies one of the largest cities in the country from groundwater alone. San Antonio Water System (SAWS) serves 2 million people.
These two cities, combined into a 2.3 million person metro, could not have more different water supply profiles. Austin drinks from surface reservoirs. San Antonio drinks from an underground river flowing through limestone.
Austin's Highland Lakes supply has shown minimal PFAS detections in UCMR5 testing. The lakes sit in the Texas Hill Country with limited industrial or military activity along their watersheds. San Antonio's situation is more complex: Joint Base San Antonio (JBSA), which includes Lackland, Randolph, and Fort Sam Houston, has documented PFAS contamination from AFFF foam use. JBSA is one of the largest military installations in the country, and its PFAS footprint has been the subject of ongoing Department of Defense investigation.
The Edwards Aquifer's karst geology is a wildcard. Karst formations have direct surface-to-aquifer pathways through sinkholes and fractures – contaminants can travel from the surface to the water table much faster than through conventional soil and rock layers. Whether JBSA's PFAS contamination has reached the production zones of the Edwards Aquifer is an active area of study.
Texas has not set state PFAS MCLs. According to TCEQ data, SAWS' water supply has shown PFAS detections below federal limits but at levels that bear monitoring given the vulnerability of the karst system.
Austin proper benefits from one of the cleaner surface water supplies among major Texas cities. The Highland Lakes system avoids the industrial contamination that affects Houston's Gulf Coast Aquifer and the agricultural runoff that burdens some North Texas reservoirs.
San Antonio faces a more unique challenge. The Edwards Aquifer is simultaneously one of the most productive and most vulnerable major aquifers in the U.S. Its karst structure means recharge happens quickly – good for replenishment, risky for contamination. Among Texas metros, San Antonio's proximity to a massive military complex with confirmed PFAS makes it the metro to watch most closely.
See our Texas state page for statewide patterns.
Austin and San Antonio face different risks. Austin residents on Highland Lakes supply have low PFAS exposure. San Antonio residents, especially those near JBSA or in areas overlying the Edwards Aquifer recharge zone, should be more attentive.
Check your water to see data for your specific system. If you're in San Antonio near a JBSA installation, reviewing your data regularly is a reasonable practice. Our water filter guide covers options appropriate for Edwards Aquifer water chemistry. A detailed report can track contamination trends as military investigations progress.