Williamson County, Tennessee: drinking water report. Williamson County south of Nashville has about 247,000 residents in one of the wealthiest and…
Williamson County south of Nashville has about 247,000 residents in one of the wealthiest and fastest-growing counties in Tennessee. Franklin and Brentwood are the main communities. Water comes from the Harpeth River and groundwater, with the Water Authority of Dickson County and Consolidated Utility District providing service. The county's rapid suburban growth is converting farmland at a pace that challenges water infrastructure.
The Harpeth River has been listed as impaired by the Tennessee DEC for elevated E. coli, nutrients, and siltation. According to the 2024 Tennessee water quality assessment, phosphorus at the Franklin gauge averaged 0.12 mg/L – driven by both urban stormwater and the remaining agricultural activity in the watershed. Treatment plants manage these inputs, but the raw water quality drives treatment complexity.
The former Vultee Aircraft factory site in Nashville and regional airport facilities have contributed PFAS to the broader Nashville-area groundwater. Tennessee DEC's 2024 investigation found PFAS at 7 ppt in one Williamson County monitoring well. The county's karst geology in the western portion creates rapid contamination pathways similar to other Middle Tennessee carbonate terrain.
Williamson County's rapid growth means the water systems are expanding to meet demand. Treated water meets all standards, but the Harpeth River's impaired status means source water quality requires sustained treatment investment.
Check your water for current data at your address. A carbon filter addresses disinfection byproducts from treated river water. For PFAS, reverse osmosis adds targeted protection. Our water filter guide covers both approaches. Pull your detailed report for trends, and visit our Tennessee page for statewide data.