Round Rock Water Hardness & Quality Report (2026)

The City of Round Rock Utilities Department provides drinking water to approximately 130,000 residents in Round Rock and parts of Williamson County, Texas. Primary sources are surface water from Lake Georgetown on the North San Gabriel River, treated at the North Fork Water Treatment Plant, and groundwater from the Edwards Aquifer via Brushy Creek Regional Utility Authority wells. The system is rated 'superior' by the Texas Commission on Environmental Quality (TCEQ) and meets all applicable federal and state water quality standards.

Water originates from the North San Gabriel River watershed feeding Lake Georgetown and the karstic Edwards Aquifer in Central Texas. The Cretaceous Edwards Limestone Formation, with its dolomite layers and solution cavities, actively dissolves carbonate minerals into the supply, yielding a hard character. The underlying Glen Rose Formation and limestone-rich soils amplify mineral content, while surface water picks up ions from regional geology — contributing to a highly mineralized supply throughout the distribution system without softening treatment.

Very hard water at 239 mg/L promotes significant scale buildup in pipes, water heaters, dishwashers, and washing machines, reducing efficiency and lifespan. Faucets, showerheads, and fixtures develop spots and soap scum, while soap lathers poorly, affecting skin and hair. Regular vinegar descaling, annual appliance checks, and installing a water softener are strongly recommended to prevent costly repairs and extend plumbing life. The utility reports pH averaging 7.5–8.0 with full lead/copper rule compliance. Treatment involves coagulation, sedimentation, filtration, chloramination, and fluoridation; disinfection byproducts (HAA5 max 32 ppb, TTHM max 54 ppb) remain within limits.