How hard is the water in Commerce City, CO?
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
The water in Commerce City carries roughly 95 mg/L of dissolved calcium and magnesium, or 5.6 grains per gallon. That is moderately hard water. The number comes from Denver Water Board, dated October 2025.
At 95 mg/L, Commerce City is close to the typical Colorado figure of 97 mg/L. Of the 10 nearest cities we track, 1 has softer water and 9 have harder. The range nearby runs from 79 mg/L in Derby to 202 in Brighton.
What 95 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.
3 people × 75 gallons a day × 5.6 gpg = 1,251 grains a day. A 24,000-grain unit regenerates about every 19 days.
EPA record for Commerce City's water system
No health-based violations since 2016
Serves about 1,287,000 people from surface water.
- Health-based
- 0
- Monitoring or reporting
- 35
- Open now
- 0
TapWaterData ties Commerce City to this system. EPA's service-area records do not name Commerce City, so check the utility printed on your water bill.
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 Commerce City water hard?
Somewhat. It measures about 95 mg/L (5.6 grains per gallon), which the USGS classes as moderately hard.
What is the water hardness in Commerce City in grains per gallon?
About 5.6 gpg. One grain per gallon equals 17.1 mg/L, so 95 mg/L divided by 17.1 gives 5.6.
What size water softener do I need in Commerce City?
For 3 people using 75 gallons each per day, 5.6 gpg works out to about 1,251 grains a day. A 24,000-grain softener covers that with a regeneration about every 19 days.
Has the Commerce City water system had EPA violations?
EPA records show no health-based violations for Denver Water Board since 2016. There were also 35 monitoring or reporting violations, which are about late or missing tests and notices.
Nearby cities
- Brighton202 mg/LVery hard
- Derby79 mg/LModerately hard
- Thornton98 mg/LModerately hard
- Welby96 mg/LModerately hard
- Denver97 mg/LModerately hard
- Northglenn118 mg/LModerately hard
- Sherrelwood100 mg/LModerately hard
- Federal Heights119 mg/LModerately hard
- Twin Lakes99 mg/LModerately hard
- Aurora100 mg/LModerately hard
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.