Knoxville Water Hardness & Quality Report (2026)

Knoxville, Tennessee draws its municipal water supply from the Knoxville Utilities Board (KUB), sourcing raw water from the Tennessee River at Fort Loudoun Lake — a Tennessee Valley Authority (TVA) impoundment created by Fort Loudoun Dam in Knox County. The Tennessee River at Knoxville represents the confluence of the French Broad and Holston Rivers, collecting drainage from extensive mountain and Valley and Ridge catchments across East Tennessee, North Carolina, and Virginia. Raw water is treated at the Niles Ferry Water Treatment Plant before distribution. Water hardness in Knoxville measures 169 mg/L — classified as hard.

Knoxville's hard water supply reflects the rich carbonate geology of the upper Tennessee watershed in the Valley and Ridge physiographic province. The Tennessee River system in East Tennessee drains folded sequences of Ordovician Knox Dolomite, Cambrian Rome Formation limestone and shale, and Ordovician Chickamauga Limestone — thick marine carbonate formations deposited in ancient Iapetus Ocean shallow seas that once covered this region. The Valley and Ridge's typical corrugated limestone and dolomite ridges and valleys are among the most calcium-rich terrains in the Eastern United States, consistently generating hard water in all surface water systems draining this province.

At 169 mg/L, Knoxville residents face regular scale build-up on bathroom fixtures, in appliances, and on glassware. Monthly descaling of showerheads and faucet aerators with citric acid or vinegar keeps fixtures performing well. Kettles accumulate a moderate mineral film that benefits from quarterly treatment. Water heaters experience progressive element scaling — an annual inspection is worthwhile to maintain efficiency. Dishwashers consistently produce cleaner results with rinse-aid to prevent white mineral spotting. KUB's water supply consistently meets all EPA and Tennessee TDEC Safe Drinking Water Act standards.