Houston Water Hardness & Quality Report (2026)

Houston's drinking water is supplied by Houston Water (a division of the City of Houston Public Works Department) from two primary reservoir sources. Lake Houston, fed by the San Jacinto River, and Lake Livingston on the Trinity River some 75 miles north of the city together provide the majority of the city's surface water supply. Houston also draws from the Gulf Coast Aquifer via a network of deep groundwater wells, though the city has deliberately shifted away from heavy groundwater reliance to address chronic land subsidence across the Houston metropolitan area. The Northeast Water Purification Plant and East Water Purification Plant process the incoming surface supply before distribution.

At 184 mg/L, Houston's water sits in the hard range — a reflection of the East Texas Coastal Plain geology through which its tributary rivers flow. The reservoirs collect runoff that has passed over Eocene-age sedimentary formations — the Wilcox Group sands, Sparta Formation, and Yegua Formation — marine and deltaic sequences deposited 35–55 million years ago as the Gulf of Mexico receded northward. These formations contain significant calcium carbonate, calcite cement, and gypsum horizons, which dissolve into the water column as rivers traverse the lowland coastal plain before reaching the reservoir intakes.

With hard water, Houston households should anticipate visible white scale deposits on showerheads, faucet aerators, and around drain rings, noticeably lower soap lather in showers and laundry, and significant scale accumulation inside kettles and water heaters over time. Appliance lifespan — particularly for water heaters and dishwashers — is reduced compared to soft-water cities. Installing a whole-house water softener is a common and practical investment in Houston, and descaling water heaters annually can extend their working life by several years.