Hard water in Norman, OK

Tap water hardness
148mg/L
8.7gpg
Hard

Reported by Oklahoma City · September 2025

OK typical
152 mg/L
EPA health violations since 2016
1
Softener for 3 people
24k grain
Data
Utility report

Tap water in Norman has about 148 mg/L of hardness, which is 8.7 grains per gallon. On the USGS scale that counts as hard. The number comes from Oklahoma City, dated September 2025.

Norman on the hardness scale, with nearby cities
060120180240300360+OK typical 152Moore: 94 mg/LMoore 94Piedmont: 123 mg/LPiedmont 123The Village: 134 mg/LThe Village 134Edmond: 135 mg/LEdmond 135Shawnee: 140 mg/LShawnee 140Newcastle: 157 mg/LNewcastle 157Oklahoma City: 157 mg/LOklahoma City 157Yukon: 157 mg/LYukon 157Bethany: 221 mg/LBethany 221Mustang: 463 mg/LMustang 463Norman 148mg/L as calcium carbonate060120180240300360+OK 152Moore: 94 mg/LMoore 94Shawnee: 140 mg/LShawnee 140Newcastle: 157 mg/LNewcastle 157Oklahoma City: 157 mg/LOklahoma C. 157Bethany: 221 mg/LBethany 221Mustang: 463 mg/LMustang 463148 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Norman sits close to the typical Oklahoma figure of 152 mg/L. Of the 10 nearest cities we track, 5 have softer water and 5 have harder. The range nearby runs from 94 mg/L in Moore to 463 in Mustang.

What 148 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 148 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.

Softener size for Norman

3 people × 75 gallons a day × 8.7 gpg = 1,953 grains a day. A 24,000-grain unit regenerates about every 12 days.

Size it for your household

EPA record for Norman's water system

Norman Utilities Authority · PWSID OK1020801

1 health-based violation since 2016

Serves about 104,868 people from surface water.

Health-based
1
Monitoring or reporting
2
Open now
0

EPA lists Norman Utilities Authority as the system serving Norman. The hardness figure above comes from a different system's report, which TapWaterData uses for Norman.

20162017201820192020202120222023202420252026Lead and Copper Rule'16'18'20'22'24'26Lead and Copper Rule
Each dot is one health-based violation, placed at the start of its compliance period.
Contaminant or ruleViolationsPeriodStatus
Lead and Copper Rulecorrosion control and lead sampling12024Resolved

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 Norman water hard?

Yes. It measures about 148 mg/L (8.7 grains per gallon), which the USGS classes as hard.

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

About 8.7 gpg. One grain per gallon equals 17.1 mg/L, so 148 mg/L divided by 17.1 gives 8.7.

What size water softener do I need in Norman?

For 3 people using 75 gallons each per day, 8.7 gpg works out to about 1,953 grains a day. A 24,000-grain softener covers that with a regeneration about every 12 days.

Has the Norman water system had EPA violations?

EPA records show 1 health-based violation for Norman Utilities Authority since 2016, involving Lead and Copper Rule. There were also 2 monitoring or reporting violations, which are about late or missing tests and notices.

Nearby cities

All 34 cities in Oklahoma

Hardness data: TapWaterData US Water Hardness (utility report, September 21, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.