How hard is the water in Aurora, CO?

Tap water hardness
100mg/L
5.8gpg
Moderately hard

Reported by Denver Water Board · October 2025

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

Tap water in Aurora has about 100 mg/L of hardness, which is 5.8 grains per gallon. On the USGS scale that counts as moderately hard. The number comes from Denver Water Board, dated October 2025.

Aurora on the hardness scale, with nearby cities
060120180240300360+CO typical 97Derby: 79 mg/LDerby 79Commerce City: 95 mg/LCommerce City 95Four Square Mile: 96 mg/LFour Square Mile 96Cherry Creek: 96 mg/LCherry Creek 96Dove Valley: 96 mg/LDove Valley 96Centennial: 96 mg/LCentennial 96Greenwood Village: 96 mg/LGreenwood Village 96Cherry Hills Village: 96 mg/LCherry Hills Village 96Meridian: 96 mg/LMeridian 96Denver: 97 mg/LDenver 97Aurora 100mg/L as calcium carbonate060120180240300360+CO 97Four Square Mile: 96 mg/LFour Squar. 96Cherry Creek: 96 mg/LCherry Cre. 96Dove Valley: 96 mg/LDove Valley 96Centennial: 96 mg/LCentennial 96Greenwood Village: 96 mg/LGreenwood. 96Denver: 97 mg/LDenver 97100 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Aurora sits close to the typical Colorado figure of 97 mg/L. None of the 10 nearest cities we track has harder water. The range nearby runs from 79 mg/L in Derby to 97 in Denver.

What 100 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 Aurora

3 people × 75 gallons a day × 5.8 gpg = 1,314 grains a day. A 24,000-grain unit regenerates about every 18 days.

Size it for your household

EPA record for Aurora's water system

Aurora City of · PWSID CO0103005

No health-based violations since 2016

Serves about 533,407 people from surface water.

Health-based
0
Monitoring or reporting
2
Open now
0

EPA lists Aurora City of as the system serving Aurora. The hardness figure above comes from a different system's report, which TapWaterData uses for Aurora.

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 Aurora water hard?

Somewhat. It measures about 100 mg/L (5.8 grains per gallon), which the USGS classes as moderately hard.

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

About 5.8 gpg. One grain per gallon equals 17.1 mg/L, so 100 mg/L divided by 17.1 gives 5.8.

What size water softener do I need in Aurora?

For 3 people using 75 gallons each per day, 5.8 gpg works out to about 1,314 grains a day. A 24,000-grain softener covers that with a regeneration about every 18 days.

Has the Aurora water system had EPA violations?

EPA records show no health-based violations for Aurora City of since 2016. There were also 2 monitoring or reporting violations, which are about late or missing tests and notices.

Nearby cities

All 64 cities in Colorado

Hardness data: TapWaterData US Water Hardness (utility report, October 7, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.