Wylie Water Hardness & Quality Report (2026)

Wylie, Texas, in Collin County northeast of Dallas — one of the fastest-growing cities in Texas, a major northeast DFW suburban community on Lake Lavon, a diverse and rapidly expanding Collin County community with significant Indian-American, Korean-American, and African-American populations, home of the Wylie East and Wylie High athletic programs — draws its municipal water supply from Lake Lavon via the North Texas Municipal Water District (NTMWD). Water hardness in Wylie measures 256.5 mg/L — classified as very hard.

Wylie's very hard supply reflects the northeast Dallas Collin County calcareous Cretaceous geology. The Lake Lavon watershed drains Collin County's Texas Blackland Prairie — the Cretaceous Austin Chalk, Taylor Group marl, and Eagle Ford Group (highly calcareous marine Cretaceous formations of the Texas Gulf Coast Plain — the Texas Blackland Prairie's primary parent rock). These highly calcareous Cretaceous formations dissolve readily in the Blackland Prairie surface drainage, producing the Lake Lavon supply with very high dissolved calcium content. NTMWD distributes the Lake Lavon supply to Wylie with minimal hardness treatment, producing the very hard 256.5 mg/L at Wylie household taps.

At 256.5 mg/L, Wylie residents face significant hard water challenges. Scale deposits form rapidly on all fixtures and tile — monthly descaling with citric acid solution is essential maintenance. North Texas Municipal Water District consistently delivers water meeting all Texas TCEQ and EPA Safe Drinking Water Act requirements.