How hard is the water in Knoxville, TN?

Tap water hardness
91mg/L
5.3gpg
Moderately hard

Reported by Knoxville Utilities Board-KUB · August 2025

TN typical
89 mg/L
EPA health violations since 2016
0
Softener for 3 people
24k grain
Data
Utility report

Tap water in Knoxville has about 91 mg/L of hardness, which is 5.3 grains per gallon. On the USGS scale that counts as moderately hard. The number comes from Knoxville Utilities Board-KUB, dated August 2025.

Knoxville on the hardness scale, with nearby cities
060120180240300360+TN typical 89Alcoa: 37 mg/LAlcoa 37Maryville: 42 mg/LMaryville 42Eagleton Village: 46 mg/LEagleton Village 46Cookeville: 56 mg/LCookeville 56Harrison: 71 mg/LHarrison 71Powell: 99 mg/LPowell 99Kingsport: 106 mg/LKingsport 106Oak Ridge: 132 mg/LOak Ridge 132Cleveland: 150 mg/LCleveland 150Morristown: 260 mg/LMorristown 260Knoxville 91mg/L as calcium carbonate060120180240300360+TN 89Alcoa: 37 mg/LAlcoa 37Maryville: 42 mg/LMaryville 42Eagleton Village: 46 mg/LEagleton V. 46Powell: 99 mg/LPowell 99Oak Ridge: 132 mg/LOak Ridge 132Morristown: 260 mg/LMorristown 26091 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

At 91 mg/L, Knoxville is close to the typical Tennessee figure of 89 mg/L. Of the 10 nearest cities we track, 5 have softer water and 5 have harder. The range nearby runs from 37 mg/L in Alcoa to 260 in Morristown.

What 91 mg/L means at home

You may see faint white spots on glasses and shower doors after the water dries.

Scale builds up slowly. A kettle or coffee maker needs descaling now and then, maybe every few months.

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

Optional. Plenty of households at this level live with it and descale the kettle now and then.

Water softener

Worth a look if spots on glass bother you, or if your tankless water heater manual asks for softer water.

Carbon filter

Improves taste and removes chlorine. It leaves calcium and magnesium in place.

Softener size for Knoxville

3 people × 75 gallons a day × 5.3 gpg = 1,202 grains a day. A 24,000-grain unit regenerates about every 19 days.

Size it for your household

EPA record for Knoxville's water system

Knoxville Utilities Board - KUB · PWSID TN0000366

No health-based violations since 2016

Serves about 254,671 people from surface water.

Health-based
0
Monitoring or reporting
1
Open now
0

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 Knoxville water hard?

Somewhat. It measures about 91 mg/L (5.3 grains per gallon), which the USGS classes as moderately hard.

What is the water hardness in Knoxville in grains per gallon?

About 5.3 gpg. One grain per gallon equals 17.1 mg/L, so 91 mg/L divided by 17.1 gives 5.3.

What size water softener do I need in Knoxville?

For 3 people using 75 gallons each per day, 5.3 gpg works out to about 1,202 grains a day. A 24,000-grain softener covers that with a regeneration about every 19 days.

Has the Knoxville water system had EPA violations?

EPA records show no health-based violations for Knoxville Utilities Board - KUB since 2016. There were also 1 monitoring or reporting violation, which are about late or missing tests and notices.

Nearby cities

All 44 cities in Tennessee

Hardness data: TapWaterData US Water Hardness (utility report, August 26, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.