Franklin Water Hardness & Quality Report (2026)
Water Hardness
6 grains per gallon
Source
reservoir
pH Level
7.6
neutral = 7.0
Lead
0.002 mg/L
✓ Below action level
TDS
168.9 mg/L
Est. Daily Cost
$0.28
energy & soap waste
Source: USGS Water Quality Portal · Updated 2026
0–60
mg/L
Soft
61–120
mg/L
Moderately Hard
121–180
mg/L
Hard
180+
mg/L
Very Hard
Appliance Damage Report
In Franklin, your appliances are currently losing 14% efficiency due to mineral buildup.
| Appliance | In Franklin | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 6.2 yrs | 8.5 yrs | -27% |
| Washing Machine | 9.8 yrs | 12 yrs | -18% |
| Water Heater | 11.5 yrs | 15 yrs | -23% |
Regional Water Comparison
How Franklin compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Franklin, Tennessee | 103.5 mg/L | 3.5 ppt | 🟡 Moderately Hard | reservoir |
| Brentwood Estates, Tennessee | 123 mg/L | 4.2 ppt | 🟠 Hard | reservoir |
| Brentwood, Tennessee | 122.5 mg/L | 4.1 ppt | 🟠 Hard | reservoir |
| Spring Hill, Tennessee | 89.5 mg/L | 3 ppt | 🟡 Moderately Hard | reservoir |
| Nashville, Tennessee | 125.5 mg/L | 4.2 ppt | 🟠 Hard | reservoir |
National Benchmark
How Franklin compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Franklin | 103.5 mg/L | 🟡 Low |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Franklin's Water Unique?
Local geology and source profile
Franklin, Tennessee, the Williamson County seat south of Nashville — one of the nation's fastest-growing cities and one of Tennessee's most affluent communities — draws its municipal water supply from the Harpeth River (a Cumberland River tributary in Williamson County) via the City of Franklin Water Management Division, treating Harpeth River water at the Franklin Water Treatment Plant. Franklin is the center of the Nashville metropolitan area's southern growth corridor. Water hardness in Franklin measures 103.5 mg/L — classified as moderately hard.
Franklin's moderate hardness reflects the Harpeth River watershed's Central Basin geology in Williamson County. The Harpeth River drains the Nashville Basin (the Tennessee Central Basin geologic dome) — exposing the remarkably complete Ordovician carbonate sequence: the Ridley Limestone, Lebanon Limestone (oolitic), Carters Limestone, and the Hermitage Formation (all Ordovician carbonates of the Nashville Dome). These Ordovician limestones, while highly calcareous, are deeply weathered and covered by the Nashville Basin's classic cedar glade terrain — thin-soiled landscapes over Ordovician limestone. The calcareous Ordovician limestone drainage produces the moderately hard supply typical of Central Basin Tennessee rivers.
At 103.5 mg/L, Franklin residents encounter moderate scale accumulation. Faucet aerators and showerheads develop deposits after several months — monthly cleaning with citric acid solution is practical maintenance. City of Franklin Water Management Division consistently delivers water meeting all Tennessee TDEC and EPA Safe Drinking Water Act requirements.
Geology & Source: River supply from the Harpeth River and the Cumberland River system via the City of Franklin Water Management Division — the Tennessee Central Basin Nashville Dome (Ordovician Carters Limestone, Lebanon Limestone, Ridley Limestone) and Devonian Chattanooga Shale of Williamson County; moderately hard supply at 103.5 mg/L in Williamson County.