Brentwood Water Hardness & Quality Report (2026)
Water Hardness
7.2 grains per gallon
Source
reservoir
pH Level
7.7
neutral = 7.0
Lead
0.003 mg/L
✓ Below action level
TDS
218.6 mg/L
Est. Daily Cost
$0.33
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 Brentwood, your appliances are currently losing 16% efficiency due to mineral buildup.
| Appliance | In Brentwood | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 5.6 yrs | 8.5 yrs | -34% |
| Washing Machine | 9.1 yrs | 12 yrs | -24% |
| Water Heater | 10.7 yrs | 15 yrs | -29% |
Regional Water Comparison
How Brentwood compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Brentwood, Tennessee | 122.5 mg/L | 4.1 ppt | 🟠 Hard | reservoir |
| Brentwood Estates, Tennessee | 123 mg/L | 4.2 ppt | 🟠 Hard | reservoir |
| Nashville, Tennessee | 125.5 mg/L | 4.2 ppt | 🟠 Hard | reservoir |
| Franklin, Tennessee | 103.5 mg/L | 3.5 ppt | 🟡 Moderately Hard | reservoir |
| La Vergne, Tennessee | 170.5 mg/L | 5.7 ppt | 🟠 Hard | reservoir |
National Benchmark
How Brentwood compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Brentwood | 122.5 mg/L | 🟠 Moderate |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Brentwood's Water Unique?
Local geology and source profile
Brentwood, Tennessee, in Williamson County south of Nashville — one of the most affluent communities in Tennessee and the United States (consistently ranked among the wealthiest cities in America), a major Nashville south suburban community in the Cool Springs commercial corridor, home of numerous Nashville country music industry executives and corporate headquarters (Tractor Supply Company, Delek Group), and a major upscale Williamson County residential community — draws its municipal water supply from the Cumberland River via the Williamson County water system and the City of Brentwood Water Division. Water hardness in Brentwood measures 122.5 mg/L — classified as moderately hard.
Brentwood's moderate hardness reflects the Williamson County Nashville Basin calcareous geology. The Williamson County water supply draws from the Cumberland River and Harpeth River watersheds draining the Nashville Basin — the Ordovician calcareous limestone and dolomite of Middle Tennessee (Catheys Formation, Bigby-Cannon Limestone, Lebanon Limestone — highly calcareous marine limestone and dolomite of the Nashville Dome, one of the most calcareous Ordovician formations in the US). The Nashville Basin calcareous limestone karst produces the moderate 122.5 mg/L at Brentwood.
At 122.5 mg/L, Brentwood residents encounter moderate scale accumulation. Monthly cleaning with citric acid solution is recommended for faucet aerators and showerheads. Williamson County Water Division consistently delivers water meeting all Tennessee TDEC and EPA Safe Drinking Water Act requirements.
Geology & Source: River supply from the Harpeth River and Cumberland River (Metro Nashville Water Services) via the Williamson County water system and City of Brentwood Water Division — the Williamson County Middle Tennessee Nashville Basin (Ordovician Nashville Dome calcareous limestone and dolomite karst); moderately hard supply at 122.5 mg/L in Williamson County.