Boulder's water is soft, so a water heater here usually wears out from age before scale gets it.
Boulder water heaters at a glance
| Water provider | City of Boulder Utilities: Barker Reservoir, North Boulder Creek, Carter Lake, and Boulder Reservoir |
|---|---|
| Water hardness | Soft: about 42 mg/L (2.4 grains per gallon) |
| Homes | Median year built 1977, and about 7.5% of homes date to 1939 or earlier |
| Elevation | About 5,319 feet (USGS reference point) |
| For your water heater | Little sediment, so a tank usually reaches its rated life. The anode rod still wears, so check it every few years. |
Sources: Boulder drinking water quality · Census ACS 2019–2023 via Point2Homes · USGS elevation. Checked October 2026.
What Boulder'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. Boulder's water averages about 42 mg/L of hardness (2.4 grains per gallon), which is soft. Little sediment, so a tank usually reaches its rated life. The anode rod still wears, so check it every few years.
Older houses, soft water
Boulder's houses run from the century-old homes around Mapleton Hill to the postwar ranches of Martin Acres and Table Mesa. With water this soft, a tank collects little sediment and can reach its rated life, so in Boulder the question is usually age: once a heater passes about 10 years, replacing it before it leaks costs less than cleaning up after one. In older houses the heater often sits in a tight basement or closet, and the shutoff valve and connectors usually get replaced with it.
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. Soft water is easy on a tankless heater. Descale it on the maker's schedule and it should go a long time between service calls.
At about 5,319 feet (Boulder'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; with water this soft it won't take long
- Check the anode rod every few years and replace it before it's used up
- Keep the area around a gas heater clear so it gets the combustion air it needs
- 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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