The Colony Water Hardness & Quality Report (2026)

The Colony, Texas, in Denton County north of Dallas on Lake Lewisville — a major master-planned Dallas north suburban lakefront community (built largely as a planned community in the 1970s–1980s), a major Dallas north suburban community with exceptional Lake Lewisville waterfront, and a diverse Denton County community in the rapidly growing north Dallas suburbs — draws its municipal water supply from Lake Lewisville via the NTMWD and the City of The Colony Water Division. Water hardness in The Colony measures 379 mg/L — classified as extremely hard.

The Colony's extremely hard supply — among the hardest municipal supplies in Texas — reflects the Lake Lewisville Elm Fork Trinity River watershed's highly calcareous Austin Chalk and Eagle Ford geology. Lake Lewisville on the Elm Fork Trinity River drains through: the Cretaceous Austin Chalk (pure marine chalk — essentially calcium carbonate, the most calcareous formation in the DFW region); the Eagle Ford Shale and Marl (calcareous marl and calcareous shale); and the Taylor Marl (highly calcareous Cretaceous marl). The exceptional Austin Chalk dissolution in the NTMWD Elm Fork Trinity watershed produces the extremely hard 379 mg/L at The Colony.

At 379 mg/L, The Colony residents face severe hard water challenges. Scale deposits form very rapidly on all fixtures — weekly descaling and appliance protection measures are strongly recommended. NTMWD consistently delivers water meeting all Texas TCEQ and EPA Safe Drinking Water Act requirements.