Texarkana Water Hardness & Quality Report (2026)

Texarkana Water Utilities (TWU) serves approximately 40,000 residents in Texarkana, Texas, and parts of Bowie County, operating as a municipal utility jointly managed with Texarkana, Arkansas. Drinking water is sourced exclusively from two surface reservoirs: Lake Wright Patman (capacity 33 billion gallons) on the Sulphur River and Lake Millwood (49 billion gallons), also on the Sulphur River. Raw water is treated at the Holly Street Treatment Plant and the Millwood Treatment Plant, employing conventional processes including coagulation, sedimentation, filtration, and disinfection with chlorine, with continuous monitoring to meet EPA and Texas standards.

The reservoirs lie within the Sulphur River watershed, spanning the Piney Woods and Post Oak Savannah ecoregions of the Gulf Coastal Plain. Underlying geology features Cretaceous sedimentary rocks such as the Austin Chalk — a highly calcareous limestone — and the Eagle Ford Group with marly shales, both contributing to mineral leaching into surface waters. No groundwater aquifers are utilized; the moderately soft supply reflects limestone dissolution in the drainage basin, with naturally low sodium and trace fluoride from bedrock weathering.

As a moderately soft supply, scale buildup can still affect water heaters, dishwashers, and coffee makers, with faucet aerators and showerheads subject to gradual clogging. Annual descaling and vinegar soaks for fixtures are recommended; a water softener may benefit households concerned about glassware spotting or skin and hair film. Water quality testing confirms compliance with federal standards; pH stabilizes around 7.5–8.0 post-treatment, PFAS were not detected in the 2023–2024 CCRs, and third-party analysis notes arsenic occasionally above health guidelines from natural soil and bedrock sources.