Guadalupe County, Texas: drinking water report. Guadalupe County between San Antonio and Austin has about 172,000 residents in fast-growing communities
Guadalupe County between San Antonio and Austin has about 172,000 residents in fast-growing communities like Seguin, New Braunfels, and Schertz. Water comes from the Edwards Aquifer, the Carrizo-Wilcox Aquifer, and the Guadalupe River. The county sits at the intersection of the Hill Country and the Coastal Plain, with dramatically different geology – and water quality – depending on which side of the Balcones Fault you live on.
The Edwards Aquifer in the western part of the county produces naturally clean, limestone-filtered water. However, the aquifer is a karst system where contamination can travel rapidly through solution channels. According to TCEQ's 2024 source water assessment, the aquifer recharge zone in Guadalupe County is under increasing development pressure as the San Antonio metro expands.
Randolph Air Force Base (now Joint Base San Antonio-Randolph) in neighboring Bexar County has documented PFAS contamination that extends into Guadalupe County. A 2024 TCEQ investigation found PFAS at 12 ppt in monitoring wells near the Schertz-Seguin area. The EPA's UCMR5 data detected PFAS in the Seguin water system.
Guadalupe County's rapid growth means water demand is straining aquifer supplies. The Edwards Aquifer's karst nature provides fast recharge but also fast contamination pathways. If you are on a well in the recharge zone, testing after heavy rains is worthwhile since that is when surface contaminants flush into the aquifer.
Check your water for current data. For PFAS, reverse osmosis provides the strongest household protection. Our water filter guide covers systems suited to Texas aquifer water. Pull your detailed report for trends, and visit our Texas page for statewide context.