How hard is the water in Prescott, AZ?

Tap water hardness
104mg/L
6.1gpg
Moderately hard

Reported by Prescott City of · September 2025

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

Prescott water measures 104 mg/L (6.1 gpg) of hardness, moderately hard by USGS standards. The number comes from Prescott City of, dated September 2025.

Prescott on the hardness scale, with nearby cities
060120180240300360+AZ typical 180Sun City: 75 mg/LSun City 75Youngtown: 75 mg/LYoungtown 75Prescott Valley: 109 mg/LPrescott Valley 109Flagstaff: 161 mg/LFlagstaff 161Glendale: 168 mg/LGlendale 168Paradise Valley: 171 mg/LParadise Valley 171Scottsdale: 172 mg/LScottsdale 172Cottonwood: 179 mg/LCottonwood 179El Mirage: 208 mg/LEl Mirage 208Phoenix: 237 mg/LPhoenix 237Prescott 104mg/L as calcium carbonate060120180240300360+AZ 180Sun City: 75 mg/LSun City 75Youngtown: 75 mg/LYoungtown 75Prescott Valley: 109 mg/LPrescott V. 109Flagstaff: 161 mg/LFlagstaff 161Cottonwood: 179 mg/LCottonwood 179El Mirage: 208 mg/LEl Mirage 208104 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Prescott sits 76 mg/L below the typical Arizona figure of 180. Of the 10 nearest cities we track, 2 have softer water and 8 have harder. The range nearby runs from 75 mg/L in Sun City to 237 in Phoenix.

What 104 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 Prescott

3 people × 75 gallons a day × 6.1 gpg = 1,368 grains a day. A 24,000-grain unit regenerates about every 17 days.

Size it for your household

EPA record for Prescott's water system

Prescott City of · PWSID AZ0413045

1 health-based violation since 2016

Serves about 42,217 people from groundwater.

Health-based
1
Monitoring or reporting
83
Open now
0
20162017201820192020202120222023202420252026Groundwater Rule'16'18'20'22'24'26Groundwater Rule
Each dot is one health-based violation, placed at the start of its compliance period.
Contaminant or ruleViolationsPeriodStatus
Groundwater Ruletreatment of well water12025Resolved

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 Prescott water hard?

Somewhat. It measures about 104 mg/L (6.1 grains per gallon), which the USGS classes as moderately hard.

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

About 6.1 gpg. One grain per gallon equals 17.1 mg/L, so 104 mg/L divided by 17.1 gives 6.1.

What size water softener do I need in Prescott?

For 3 people using 75 gallons each per day, 6.1 gpg works out to about 1,368 grains a day. A 24,000-grain softener covers that with a regeneration about every 17 days.

Has the Prescott water system had EPA violations?

EPA records show 1 health-based violation for Prescott City of since 2016, involving Groundwater Rule. There were also 83 monitoring or reporting violations, which are about late or missing tests and notices.

Nearby cities

All 42 cities in Arizona

Hardness data: TapWaterData US Water Hardness (utility report, September 13, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.