Knoxville, Tennessee sits at the heart of the Tennessee Valley, drawing its drinking water from the Tennessee River system — specifically from Fort Loudoun Lake, a TVA reservoir on the Tennessee River. The Knoxville Utilities Board serves about 250,000 people and treats approximately 45 million gallons per day.
The Tennessee River is one of the most dammed river systems in the world, managed by the Tennessee Valley Authority since the 1930s. That management has brought flood control, hydroelectric power, and economic development to the region. It’s also created a complicated water quality legacy.
TVA Coal Ash: The Elephant in the Valley
The Tennessee Valley Authority operated coal-fired power plants across the region for decades, and many of those plants stored their coal combustion residuals — coal ash — in unlined ponds near waterways. The 2008 Kingston Fossil Plant disaster, about 40 miles west of Knoxville, was the worst coal ash spill in U.S. history. Over 5.4 million cubic yards of wet coal ash burst through a containment dike and flooded the Emory River, a tributary of the Tennessee.
The Kingston spill contaminated waterways with arsenic, lead, mercury, selenium, and other heavy metals. Cleanup workers have experienced serious health consequences, and the environmental effects are still being studied nearly two decades later.
While the Kingston plant is upstream of Knoxville’s drinking water intake, other TVA coal ash sites are closer. The Bull Run Fossil Plant in Clinton, Tennessee — just 20 miles north of Knoxville — has documented coal ash groundwater contamination. TVA has been working on closure and remediation of ash ponds at Bull Run and other facilities under EPA’s Coal Combustion Residuals rule.
For Knoxville’s drinking water, the city’s treatment plant is equipped to handle the contaminants associated with coal ash at the trace levels found in the river. But the cumulative effect of multiple coal ash sites along the Tennessee River system is a legitimate concern that requires ongoing monitoring.
Lead Service Lines and Aging Pipes
Knoxville’s water distribution system dates back to the early 1900s in some areas. The Knoxville Utilities Board has been conducting a lead service line inventory as required under the EPA’s revised Lead and Copper Rule.
The city’s 90th percentile lead levels have historically been well below the 15 ppb action level. KUB uses a combination of pH adjustment and corrosion inhibitor to minimize lead leaching from pipes and solder. But as with any older city, individual homes — especially those built before 1986 — can have elevated lead levels depending on their interior plumbing.
KUB offers free lead testing to residential customers, which is worth taking advantage of.
Agricultural and Development Runoff
East Tennessee’s geography — the Ridge and Valley province between the Smokies and the Cumberland Plateau — channels agricultural and urban runoff into the Tennessee River system. Knox County has seen substantial development pressure over the past two decades, and the conversion of farmland to subdivisions and commercial areas increases stormwater runoff carrying sediment, nutrients, and contaminants into tributaries.
Upstream agricultural operations contribute nitrates and phosphorus to the river system. While Knoxville’s treatment plant handles these effectively, the raw water quality fluctuates seasonally — particularly after heavy rains and during summer when algal growth increases.
PFAS: Emerging Concerns
Tennessee has been slower than some states to adopt PFAS monitoring requirements, but federal rules are changing that. The EPA’s national PFAS drinking water standards (4 ppt for PFOA, 4 ppt for PFOS) apply to all community water systems. KUB has conducted initial PFAS testing as required, and results have been below federal limits.
However, the McGhee Tyson Air National Guard Base and the Knoxville airport share a facility south of the city where AFFF was historically used. PFAS investigation is underway, and nearby groundwater users should be aware of the potential for contamination.
What Residents Can Do
- Request a lead test. KUB offers free lead testing for residential customers. Take advantage of it.
- Filter if concerned. A point-of-use carbon filter (NSF/ANSI 53) handles lead, THMs, and many other contaminants.
- Private well owners in Knox County: Test for lead, nitrates, bacteria, and consider PFAS testing if you’re near McGhee Tyson or any industrial facility.
- Stay informed. KUB publishes an annual Consumer Confidence Report with detailed water quality data. Read it.
If you’re concerned about your water quality, a certified water treatment professional can test your water and recommend the right solution for your home.
For more Tennessee coverage, see our report on Chattanooga water quality.
Sources: Knoxville Utilities Board, TVA Environmental Reports, EPA SDWIS, Tennessee Department of Environment and Conservation, USGS