San Angelo Water Hardness & Quality Report (2026)

San Angelo, Texas, the Tom Green County seat in the West Texas Concho Valley, draws its municipal water supply through the City of San Angelo Water Utilities, sourcing from the Concho River system via O.C. Fisher Lake (North Concho River) and Lake Nasworthy on the North Concho in Tom Green County, supplemented by Twin Buttes Reservoir on the Middle and South Concho Rivers southwest of San Angelo. The Concho River drains the southern Edwards Plateau — the Cretaceous limestone plateau of Central Texas — and the Permian Red Beds terrain of the Rolling Plains west of the plateau. Water hardness reaches 221.5 mg/L — classified as very hard.

San Angelo's very hard supply reflects the highly calcareous geology of the Concho River watershed in West Texas. The North and South Concho Rivers drain the southern margin of the Edwards Plateau — underlain by the Cretaceous Edwards Limestone, Comanche Peak Limestone, and Walnut Formation (the central Texas limestone plateau formations famous for extremely hard spring water). The Concho watershed also crosses Permian San Angelo Formation (calcareous sandstone), Permian Clear Fork Group (dolomite and evaporite), and Permian Leonardian calcareous formations of the Rolling Plains. This combination of Cretaceous limestone plateau and Permian calcareous terrain produces extremely mineralised surface runoff and groundwater inflow to the Concho system.

At 221.5 mg/L, San Angelo residents face significant scale challenges throughout the home. Heavy calcium deposits form on shower glass, tile, chrome, and faucet aerators within weeks — monthly descaling with citric acid solution is essential maintenance. Dishwashers require rinse-aid and periodic internal descaling, and water heaters benefit from annual professional inspection for element scale. City of San Angelo Water Utilities consistently delivers water meeting all Texas TCEQ and EPA Safe Drinking Water Act requirements.