Allen Water Hardness & Quality Report (2026)

The City of Allen Public Works Department purchases wholesale treated water from the North Texas Municipal Water District (NTMWD), serving over 105,000 residents in Allen, Texas, in Collin County. NTMWD sources raw water primarily from Lavon Lake, treated at the Wylie Water Treatment Plant. Additional supply rights include Lake Texoma, Jim Chapman Lake (Cooper Lake), Lake Tawakoni, and the East Fork Raw Water Supply Project wetlands. Water is delivered to Allen's ground storage tanks for citywide distribution.

Lavon Lake is impounded on the East Fork of the Trinity River in Collin County, whose watershed is underlain by Cretaceous-age limestone and chalk formations — notably the Woodbine Group and Austin Chalk — that dissolve to impart minerals to the supply. No major aquifer is directly tapped; surface water dominates the blend. This carbonate geology yields a moderately hard supply through natural leaching of calcium and magnesium, with additional mineral influence from Quaternary alluvium and glacial till in the basin.

Moderately hard water promotes scale buildup in water heaters, dishwashers, washing machines, and faucets, increasing energy bills and detergent use over time. Regular descaling, vinegar rinses, and low-flow aerators help mitigate deposits; a water softener is recommended for households to prevent spotting, extend appliance life, and improve soap efficiency. Allen maintains EPA compliance using chloramines for disinfection, with fluoride added at 0.537–0.968 ppm (below the 4 ppm MCL). Third-party testing flags arsenic above health guidelines from natural soil sources, along with haloacetic acids, nitrates, nitrites, and simazine; no specific PFAS or lead/copper violations are reported, and treatment includes filtration, disinfection, and corrosion control at NTMWD plants.