Hard water in Oak Ridge, TN
Reported by Oak Ridge Dept of Public Works · April 2025
- TN typical
- 89 mg/L
- EPA health violations since 2016
- 1
- Softener for 3 people
- 24k grain
- Data
- Utility report
Tap water in Oak Ridge has about 132 mg/L of hardness, which is 7.7 grains per gallon. On the USGS scale that counts as hard. The number comes from Oak Ridge Dept of Public Works, dated April 2025.
At 132 mg/L, Oak Ridge is 43 mg/L above the typical Tennessee figure of 89. Of the 10 nearest cities we track, 8 have softer water and 2 have harder. The range nearby runs from 37 mg/L in Alcoa to 260 in Morristown.
What 132 mg/L means at home
Expect white crust on faucets and showerheads, plus spots on dishes that come out of the dishwasher.
Kettles collect scale quickly. Water heaters build up sediment at the bottom of the tank, which makes them work harder over time.
Soap and detergent need a little more to lather, and soap scum shows up in the tub.
Hardness is not a health problem, and EPA sets no limit for it. It is a matter of scale and soap.
What to do about it
At 132 mg/L most of the trouble is scale, and only a few things deal with it.
Ion-exchange water softener
The standard whole-house fix. It swaps calcium and magnesium for sodium or potassium and needs salt plus a drain. Size it with the calculator below.
Salt-free conditioner
No salt and no drain line. It changes how minerals form scale instead of removing them, so water still tests hard.
Reverse osmosis or carbon filter
Under-sink reverse osmosis removes minerals from drinking water only. Plain carbon filters improve taste but do not soften.
3 people × 75 gallons a day × 7.7 gpg = 1,737 grains a day. A 24,000-grain unit regenerates about every 13 days.
EPA record for Oak Ridge's water system
1 health-based violation since 2016
Serves about 41,614 people from surface water.
- Health-based
- 1
- Monitoring or reporting
- 2
- Open now
- 1
| Contaminant or rule | Violations | Period | Status |
|---|---|---|---|
| Surface Water Treatment Rule (LT2)filtration and disinfection | 1 | 2019 | Resolved |
Health-based means a contaminant above its legal limit or a missed treatment step. Monitoring and reporting violations are late or missing tests and notices. Source: EPA ECHO, 2026Q3 export, violations with periods starting 2016 or later. Full EPA record.
Questions
Is Oak Ridge water hard?
Yes. It measures about 132 mg/L (7.7 grains per gallon), which the USGS classes as hard.
What is the water hardness in Oak Ridge in grains per gallon?
About 7.7 gpg. One grain per gallon equals 17.1 mg/L, so 132 mg/L divided by 17.1 gives 7.7.
What size water softener do I need in Oak Ridge?
For 3 people using 75 gallons each per day, 7.7 gpg works out to about 1,737 grains a day. A 24,000-grain softener covers that with a regeneration about every 13 days.
Has the Oak Ridge water system had EPA violations?
EPA records show 1 health-based violation for Oak Ridge Dept of Public Works since 2016, involving Surface Water Treatment Rule (LT2). There were also 2 monitoring or reporting violations, which are about late or missing tests and notices.
Nearby cities
- Powell99 mg/LModerately hard
- Knoxville91 mg/LModerately hard
- Alcoa37 mg/LSoft
- Maryville42 mg/LSoft
- Eagleton Village46 mg/LSoft
- Morristown260 mg/LVery hard
- Cleveland150 mg/LHard
- Cookeville56 mg/LSoft
- Harrison71 mg/LModerately hard
- Red Bank70 mg/LModerately hard
Hardness data: TapWaterData US Water Hardness (utility report, April 29, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.