Williamson County, Texas: drinking water report. Williamson County sits north of Austin, home to about 650,000 residents in one of the fastest-growing…
Williamson County sits north of Austin, home to about 650,000 residents in one of the fastest-growing counties in Texas. Cities like Round Rock, Cedar Park, and Georgetown draw water from different sources – the Brazos River Authority's Lake Georgetown, Lake Stillhouse Hollow, and the Edwards Aquifer for some western communities. The county's explosive growth has put pressure on both water supply and treatment infrastructure.
Williamson County's water systems have generally maintained good compliance records. The surface water reservoirs draw from relatively clean Hill Country watersheds, though development pressure is increasing runoff into source waters. UCMR5 data shows low-level PFAS detections in some county systems, without the military point sources that affect neighboring counties.
Water hardness is a common concern. The Edwards Limestone aquifer and Hill Country reservoirs produce naturally hard water. According to the City of Round Rock's 2024 water quality report, TDS levels averaged around 380 mg/L – enough to cause noticeable scale buildup but within EPA secondary standards.
Williamson County's rapid growth means new development areas may experience temporary water quality variability. Established systems are generally performing well.
Check your water for data in your area. A water softener addresses hardness; a reverse osmosis system under the sink handles taste, TDS, and PFAS. Our water filter guide covers both. Pull your detailed report, and visit our Texas page for statewide data.