Austin Water Hardness & Quality Report (2026)

Austin's water supply is managed by Austin Water, a City of Austin department drawing from two reservoirs on the Colorado River: Lake Travis (formed by Mansfield Dam) and Lake Austin (formed by Tom Miller Dam), together holding the primary water supply for the Austin metro area. The Ullrich Water Treatment Plant and Davis Water Treatment Plant process incoming water before distribution. Austin also maintains access to Lake Marble Falls and other Colorado River chain-of-lakes reservoirs upstream through cooperative water rights management with the Lower Colorado River Authority (LCRA), which regulates flows through the Highland Lakes system during drought and flood conditions.

Austin's hard water at 215 mg/L is a consequence of the Edwards Plateau geology through which its Colorado River tributaries flow. The Highland Lakes watershed drains the central Texas Hill Country, underlain by the Lower Cretaceous Edwards Formation, Glen Rose Limestone, and Fredericksburg Group — thick marine carbonate sequences deposited 95–110 million years ago in a shallow Cretaceous sea. These highly soluble limestone formations yield large quantities of calcium and magnesium carbonate to passing water, and recharge zones for the Edwards Aquifer in the same watershed contribute similarly mineralized groundwater inputs to the river system throughout the year.

Austin residents with hard water notice white chalky scale on showerheads, faucet spouts, and inside coffee machines and electric kettles that builds up noticeably within weeks after cleaning. Washing machines and dishwashers require regular maintenance to prevent mineral deposits on drum internals and spray arms. Descaling kettles and coffee machines monthly with citric acid or white vinegar is standard practice, and Austin homeowners commonly install whole-house water softeners to protect high-value appliances and plumbing. Rinse-aid in dishwashers is particularly important to prevent spotty glassware in Austin's very hard water conditions.