Durant Water Hardness & Quality Report (2026)

Durant, Oklahoma, in Bryan County — the Bryan County seat adjacent to Ardmore and Sherman (Texas) on Lake Texoma in south Oklahoma, the county seat near the Oklahoma-Texas border — receives its municipal water from the Durant Water Division, drawing from Lake Texoma (Red River, Bryan County) through the Durant treatment plant.

The extremely hard 373.5 mg/L hardness and very high TDS of 985.3 mg/L reflect the Red River-Lake Texoma watershed's intense Permian evaporite-calcareous character — similar to the extreme west Texas Gulf Coast readings. Lake Texoma is fed by the Red River and Washita River, which drain the Texas-Oklahoma Rolling Plains — Permian Blaine Formation (gypsum-anhydrite evaporite — the dominant dissolved solids contributor to the Red River), Permian Whitehorse Group (calcareous red shale-siltstone), and the Permian Flowerpot Shale (evaporitic). The Red River is famously highly mineralized from Permian evaporite dissolution, producing one of the hardest lake supplies in the southern Plains.

At 373.5 mg/L with TDS 985, Durant's water is extremely hard. A water softener is essential and critical. Scale forms immediately on all surfaces, appliance lifespans are critically shortened, and water heaters fail within 2-3 years without softening. The PFAS level of 6.4 ppt warrants a certified drinking water filter — the Bryan County agricultural corridor, the Lake Texoma drainage area land use, and the south Oklahoma PFAS background contribute to Durant's readings.