Denver's water is only moderately hard. In Denver, the bigger water heater problems come from old houses.
Denver water heaters at a glance
| Water provider | Denver Water |
|---|---|
| Water hardness | About 105 mg/L on average in 2025 (roughly 6 grains per gallon), ranging from 55 to 124 mg/L. Moderately hard, and a little harder in winter. |
| Homes | Median year built 1975, and about 1 in 6 homes dates to 1939 or earlier |
| Elevation | About 5,276 feet (USGS reference point) |
| For your water heater | Moderate scale. A yearly flush and an anode check every few years keep a tank close to its rated life. |
Sources: Denver Water 2026 water quality report · Census ACS 2019–2023 via Point2Homes · USGS elevation. Checked October 2026.
What Denver's water does to a water heater
When water is heated, the calcium and magnesium in it drop out as sediment and settle on the bottom of the tank. The burner or lower element then has to heat through that layer, so the heater runs longer, pops and rumbles, and wears faster. Denver Water's water averaged about 105 mg/L of hardness in 2025 (about 6 grains per gallon), a little harder in winter. Moderate scale. A yearly flush and an anode check every few years keep a tank close to its rated life.
Old Denver houses, tight utility rooms
In neighborhoods like Highland, Sunnyside, Berkeley, Park Hill, and around City Park, the water heater usually lives in a basement utility room that was built around a much smaller tank. Newer heaters are often taller and wider than the one they replace, so the space, the doorway, the shutoff valve, and the venting all need a look before a replacement is quoted. Old shutoff valves that won't fully close are common in these houses, and it's worth replacing one while the water is off anyway.
Repair or replace?
Under about eight years old, with a failed part like a thermocouple, gas valve, heating element, or thermostat, a repair usually makes sense. At about ten years or older, or with any leak from the tank itself, replacement is the better money: a leaking tank can't be fixed. You get the price before any work starts, and most replacements are done the same day they're quoted, with the old unit hauled away. A replacement is also the time to check whether you need an expansion tank (when one is required).
Gas or electric, tank or tankless
We repair and replace both gas and electric water heaters, standard tanks and tankless units. Tankless works well at this hardness. Descale it about once a year so scale doesn't choke the heat exchanger.
At about 5,276 feet (Denver's USGS reference point), a gas water heater has to be rated for the altitude, and a tankless heater set for it at installation. Rinnai and Navien change their tankless settings at 5,400 feet, and elevations vary across the city, so the setting should match your address. What to check at altitude.
Make the next one last
- Flush the tank once a year to clear sediment
- Check the anode rod every few years
- Descale a tankless unit about once a year
- Know where the cold-water shutoff on top of the heater is, and how to turn the heater off, before you need to
More reading: water heater leaking? what to do, no hot water troubleshooting, how long water heaters last in Colorado, why a water heater pops or rumbles, and water hardness by city. If your water is hard, a softener protects the heater and every fixture.
Recent water heater work
Photos from our own jobs. Locations and customer details are left out.
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