How hard is the water in San Tan Valley, AZ?

Tap water hardness
109mg/L
6.4gpg
Moderately hard

Reported by EPCOR - San Tan · May 2025

AZ typical
180 mg/L
EPA health violations since 2016
2
Softener for 3 people
24k grain
Data
Utility report

Tap water in San Tan Valley has about 109 mg/L of hardness, which is 6.4 grains per gallon. On the USGS scale that counts as moderately hard. The number comes from EPCOR - San Tan, dated May 2025.

San Tan Valley on the hardness scale, with nearby cities
060120180240300360+AZ typical 180Sun Lakes: 103 mg/LSun Lakes 103Florence: 109 mg/LFlorence 109Chandler: 139 mg/LChandler 139Gilbert: 168 mg/LGilbert 168Guadalupe: 172 mg/LGuadalupe 172Queen Creek: 178 mg/LQueen Creek 178Tempe: 180 mg/LTempe 180Casa Grande: 220 mg/LCasa Grande 220Maricopa: 220 mg/LMaricopa 220Eloy: 343 mg/LEloy 343San Tan Valley 109mg/L as calcium carbonate060120180240300360+AZ 180Sun Lakes: 103 mg/LSun Lakes 103Florence: 109 mg/LFlorence 109Chandler: 139 mg/LChandler 139Gilbert: 168 mg/LGilbert 168Queen Creek: 178 mg/LQueen Creek 178Casa Grande: 220 mg/LCasa Grande 220109 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 109 mg/L, San Tan Valley is 71 mg/L below the typical Arizona figure of 180. Of the 10 nearest cities we track, 1 has softer water and 8 have harder. The range nearby runs from 103 mg/L in Sun Lakes to 343 in Eloy.

What 109 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 San Tan Valley

3 people × 75 gallons a day × 6.4 gpg = 1,433 grains a day. A 24,000-grain unit regenerates about every 16 days.

Size it for your household

EPA record for San Tan Valley's water system

EPCOR - San Tan · PWSID AZ0411128

2 health-based violations since 2016

Serves about 87,435 people from groundwater.

Health-based
2
Monitoring or reporting
53
Open now
0
20162017201820192020202120222023202420252026Nitrate'16'18'20'22'24'26Nitrate
Each dot is one health-based violation, placed at the start of its compliance period.
Contaminant or ruleViolationsPeriodStatus
Nitrateoften from fertilizer or septic systems22016–2017Resolved

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 San Tan Valley water hard?

Somewhat. It measures about 109 mg/L (6.4 grains per gallon), which the USGS classes as moderately hard.

What is the water hardness in San Tan Valley in grains per gallon?

About 6.4 gpg. One grain per gallon equals 17.1 mg/L, so 109 mg/L divided by 17.1 gives 6.4.

What size water softener do I need in San Tan Valley?

For 3 people using 75 gallons each per day, 6.4 gpg works out to about 1,433 grains a day. A 24,000-grain softener covers that with a regeneration about every 16 days.

Has the San Tan Valley water system had EPA violations?

EPA records show 2 health-based violations for EPCOR - San Tan since 2016, involving Nitrate. There were also 53 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, May 13, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.