Fort Smith Water Hardness & Quality Report (2026)

Fort Smith, Arkansas, the second-largest city in Arkansas in Sebastian County at the Oklahoma border, draws its municipal water supply from the Arkansas River via the City of Fort Smith Water and Sewer Committee, operating a raw water intake on the Arkansas River in Fort Smith. The Arkansas River at Fort Smith collects drainage from the Ouachita Mountains and the Arkoma Basin of western Arkansas and eastern Oklahoma. Water hardness measures 179 mg/L — classified as hard.

Fort Smith's hard supply reflects the Arkansas River's accumulated mineral load at the western Arkansas reach. The Arkansas River at Fort Smith drains: the Ouachita Mountains (Mississippian and Pennsylvanian Stanley Shale, Jackfork Sandstone, Ouachita Formation — siliceous, low hardness); the Arkoma Basin (Pennsylvanian clastic formations — moderate mineral contribution); and substantial upstream drainage from the Kansas and Colorado tributaries (the Arkansas River headwaters in Colorado cross calcareous Permian redbeds and the calcareous Greenhorn Limestone). Additionally, the Canadian River (from the Oklahoma Panhandle) contributes drainage from the highly calcareous Oklahoma and Texas Panhandle formations. The net effect at Fort Smith is moderately hard supply from the cumulative calcareous upper Arkansas Basin drainage.

At 179 mg/L, Fort Smith residents face regular hard water challenges. Scale deposits form on faucet aerators, showerheads, shower glass, and tile within weeks — monthly descaling with citric acid solution is standard maintenance. Dishwashers require rinse-aid, and water heaters benefit from annual inspection. City of Fort Smith Water and Sewer Committee consistently delivers water meeting all Arkansas DWS–ADEM and EPA Safe Drinking Water Act requirements.