Richardson Water Hardness & Quality Report (2026)

Richardson, Texas, a major Dallas suburb in Collin and Dallas Counties known as the 'Telecom Corridor,' draws its municipal water supply through the City of Richardson Water Utilities, sourcing from the North Texas Municipal Water District (NTMWD) regional system, drawing from Lake Lavon on the East Fork Trinity River in Collin County and treated water through the NTMWD interconnected system. Richardson is served by a blend of NTMWD regional water and Dallas Water Utilities interconnects. Water hardness in Richardson reaches 255.5 mg/L — classified as very hard, reflecting the East Fork Trinity Blackland Prairie carbonate geology.

Richardson's very hard supply reflects the pervasive Cretaceous Austin Chalk and Taylor Marl geology of the East Fork Trinity River watershed in Collin County. Lake Lavon collects drainage from the northern DFW Blackland Prairie, where the Austin Chalk (Cretaceous marine chalk — a pure calcium carbonate formation deposited as deep-sea chalk) and the overlying Taylor Marl (calcareous marine clay) dominate the bedrock. The Blackland Prairie soils — expansive montmorillonite clay derived from these Austin Chalk parent rocks — are extraordinarily calcium-rich, and every rain event dissolves abundant calcium bicarbonate from this carbonate-saturated landscape. The East Fork Trinity system, entirely within the Blackland Prairie zone, accumulates high mineral loads with no softer source water dilution.

At 255.5 mg/L, Richardson residents face significant scale challenges. Calcium deposits form rapidly on faucet aerators, showerheads, shower glass, and tile — bi-weekly to monthly cleaning with citric acid descaler is standard practice. Dishwashers require rinse-aid for acceptable glassware, and water heaters benefit from annual professional inspection. Richardson Water Utilities and NTMWD consistently deliver water meeting all Texas TCEQ and EPA Safe Drinking Water Act requirements.