Lifespan by type
| Type | Department of Energy | Fannie Mae useful life (apartments) |
|---|---|---|
| Storage tank (gas or electric) | 10–15 years | 10 years (in-unit domestic hot water) |
| Tankless (demand) | About 20 years | 10 years (instantaneous); 15 (external) |
| Heat pump (hybrid) | 10–15 years | Not listed |
The two sources measure different things. DOE gives the range a household unit typically lasts; Fannie Mae gives the "standardized average" life a property inspector budgets for, and tells inspectors to adjust it for maintenance and environment.
How to read your water heater's age
- Find the rating plate on the side of the tank or unit. Many list a manufacture date; if not, the first digits of the serial number usually encode it, and the maker's website explains the code.
- Check the address's permit history on your city's portal: the last water heater permit's issue date is when the current unit went in, if it was permitted.
- Compare the age with the table above. Over 10 years for a tank, price a replacement now; our repair or replace guide has the decision table.
What a replacement is filed at
| City | Water heater permits (3 years) | Usual filed value | Usual days, issue to final | Reached final |
|---|---|---|---|---|
| Sacramento County, CA | 3,553 | $3,695 | 38 | 71.7% |
| Elk Grove, CA | 2,078 | $3,150 | 23 | 79.4% |
| Cary, NC | 1,519 | $4,253 | 16 | 92.9% |
| Boulder, CO | 1,267 | $3,518 | 137 | 50.9% |
| Citrus Heights, CA | 938 | $3,195 | 40 | 66.8% |
| Marin County, CA | 470 | $4,200 | 56 | 71.7% |
Replacements are seasonal: Sacramento County's busiest month for water heater permits, February, ran at 137 against 100 for an average month, and its quietest was November. An old tank replaced in the quiet season is easier to schedule. Note the finished share: only 50.9% of Boulder's water heater permits a year or more old reached a final inspection, against 92.9% in Cary. Ask the plumber who books the final.
If you are changing type, our tankless vs tank guide compares them.
Check a plumber in five minutes
- Open your city's water heater compare page (for example Sacramento County).
- Check the firm's permit count and finished share against the city's 71.7%.
- Compare the quote with the city's usual filed value on its cost page.
See every Sacramento County water heater installer →
What this does not tell you
Permits do not record the age or type of the unit removed, so we cannot measure lifespans; those come from the DOE and Fannie Mae. Filed values mix tank, tankless and heat pump units. Only eight of our cities record values on water heater permits, most of them in California.
How we know this
Water heater permits are those each city files under a water heater work type in its three-year window ending September 2026. The usual filed value is the median of permits that carry one; days is the median from issue to final; "reached final" is the share of permits a year or more old that the city closed with a final; the busiest-month index compares a month's permits with an average month. Lifespans are from the Department of Energy and Fannie Mae, read 22 October 2026.
Numbers come from Sacramento County building permits on single-family, duplex and townhouse homes in the unincorporated county (the County's Accela permit layer); City of Elk Grove TRAKiT building permits on single-family, duplex, mobile-home and ADU homes; Town of Cary building permit applications (issued permits only); City of Boulder construction permits; Marin County Community Development Agency building permits on homes in unincorporated Marin (the County's open-data permit and inspection files); City of Citrus Heights building permits on homes (the city's issued-permits layer), data through October 17, 2026. Nobody paid to be on this page and nobody can.
Questions
- How long does a tank water heater last?
10 to 15 years, according to the Department of Energy. Fannie Mae's useful-life tables, used to budget apartment buildings, give an in-unit water heater 10 years.
- How long does a tankless water heater last?
About 20 years, says the Department of Energy. Fannie Mae's apartment tables are more cautious, at 10 years for an instantaneous (tankless) unit and 15 for an external one.
- How long does a heat pump water heater last?
About 10 to 15 years, the same as a tank (Department of Energy). The DOE adds that it can be 2 to 3 times more efficient than an electric resistance heater, and that ENERGY STAR models can save almost $300 a year.
- When should you replace a water heater?
The DOE says that if your unit is nearing the 10–15 year range, start looking now, so you choose the replacement instead of buying in an emergency. A replacement was usually filed at $3,150 in Elk Grove and $4,253 in Cary.
- Is there still a tax credit for a heat pump water heater?
No federal one. The IRS says the 25C credit is not allowed for property placed in service after December 31, 2025. Utility rebates are separate; ask your utility.
Build your own list
Every firm with that kind of permit on record. Pick what you value. The list moves.
Related guides
- Which Water Heater Is Right for You? — U.S. Department of Energy, Energy Saver (2022-02-28; accessed 2026-10-22)
- Instructions for Performing a Multifamily Property Condition Assessment, Appendix F: Estimated Useful Life Tables — Fannie Mae (2019-08; accessed 2026-10-22)
- FAQs for modification of sections 25C, 25D, 25E, 30C, 30D, 45L, 45W, and 179D under Public Law 119-21 (FS-2025-05) — IRS (2025-08-21; accessed 2026-10-22)