Duncanville Water Hardness & Quality Report (2026)

Duncanville, Texas, in Dallas County — a major southwestern Dallas suburb, a historically working-class and middle-class Dallas south suburb, home of the nationally prominent Duncanville High School athletic programs (Duncanville Panthers football — one of the most storied Texas high school football programs), a diverse Dallas County community with significant African-American, Latino-American, and Asian-American populations, and a major Dallas south-suburban community rapidly transitioning to a diverse urban suburb — draws its municipal water supply from the Trinity River reservoir system via the Dallas Water Utilities (DWU). Water hardness in Duncanville measures 374.5 mg/L — classified as extremely hard.

Duncanville's extremely hard supply reflects the Dallas County Trinity River Blackland Prairie's extreme calcareous geology. The Trinity River system at Dallas drains through: the Cretaceous Austin Chalk (the signature ultra-calcareous formation of the Dallas–Fort Worth Blackland Prairie — pure marine chalk, nearly 100% calcium carbonate); the Cretaceous Taylor Marl (calcareous marine marl, 60–80% calcium carbonate); the Cretaceous Eagle Ford Shale (calcareous marine shale); and Permian calcareous red beds from the upper Trinity watershed. Dallas Water Utilities applies minimal softening, and the extreme Blackland Prairie calcareous geology produces the extreme 374.5 mg/L in Duncanville distribution.

At 374.5 mg/L, Duncanville residents face severe hard water challenges. Weekly descaling and appliance protection measures are strongly recommended. Dallas Water Utilities consistently delivers water meeting all Texas TCEQ and EPA Safe Drinking Water Act requirements.