Denton Water Hardness & Quality Report (2026)

Denton Public Works operates the water utility for the City of Denton, Texas, and surrounding areas in Denton County, part of the Dallas-Fort Worth metroplex. Primary sources are surface water from Lake Lewisville and Lake Ray Roberts, two large reservoirs impounded on the Elm Fork and main stem of the Trinity River, respectively. Raw lake water is treated at the Denton Water Treatment Plant using conventional coagulation, sedimentation, filtration, and disinfection to meet federal and state standards.

The reservoirs lie within the Trinity River Basin watershed, spanning the Blackland Prairie and North Central Texas physiographic provinces. Underlying geology features Cretaceous limestone formations including the Woodbine, Austin Chalk, and Eagle Ford groups, interspersed with marls and shales. These carbonate-rich strata contribute dissolved minerals to surface runoff and lake inflows, resulting in a hard supply influenced by the region's karst topography and proximity to Trinity Aquifer recharge zones, without reliance on deep groundwater extraction.

Very hard water promotes significant scale buildup in pipes, water heaters, dishwashers, and washing machines, reducing efficiency and lifespan while increasing energy costs; dry skin, soap scum, and dish spotting are common household effects. Regular deliming, installing scale inhibitors, or using a water softener is strongly recommended to protect plumbing infrastructure. Annual Consumer Confidence Reports confirm EPA compliance — pH typically in the 7–8 range, Lead and Copper Rule action levels not exceeded, and no notable PFAS detections; trace disinfection byproducts and naturally occurring minerals are managed through chlorination and filtration.