Texarkana Water Hardness & Quality Report (2026)

Texarkana, Texas, the Bowie County seat — a major border city straddling the Texas–Arkansas state line (Texarkana is the largest city in the United States that straddles a state line — the US Post Office on State Line Avenue famously sits exactly on the Texas–Arkansas border, with customers able to stand in both states simultaneously), home of the United States Federal Building and Post Office, a major I-30 commercial hub for the four-corners region of Texas, Arkansas, Oklahoma, and Louisiana, and a diverse Bowie County community — draws its municipal water supply from the Sulphur River (Lake Wright Patman) via the City of Texarkana Texas Water Division. Water hardness in Texarkana measures 337 mg/L — classified as extremely hard.

Texarkana's extremely hard supply reflects the northeast Texas Eocene Gulf Coastal Plain's highly calcareous geology. The Sulphur River at Lake Wright Patman drains: the Eocene Wilcox Group (highly calcareous lignite-bearing marine clay and sand of the northeast Texas Coastal Plain — the calcareous Gulf Coast Eocene formation with calcareous marine carbonate); the Eocene Claiborne Group (calcareous marine sand and clay); and the Quaternary calcareous alluvial terrace deposits of the Sulphur River. City of Texarkana applies limited lime softening, producing the extreme 337 mg/L.

At 337 mg/L, Texarkana residents face severe hard water challenges. Water softeners are essentially a necessity. City of Texarkana Texas Water Division consistently delivers water meeting all Texas TCEQ and EPA Safe Drinking Water Act requirements.