Section · Care
Water Heater Maintenance by Type
Water heater maintenance comes down to a yearly visit: flush a tank and check its anode and relief valve, descale a tankless unit, and clean a heat pump's air filter.
Compiled by the Tank & Tankless desk · Revised
At a glance
- The A. O. Smith gas manual sets the first tank drain and flush at 6 months, then at least yearly.
- Test the T&P relief valve lever at least once a year; DOE Energy Saver (archived) suggested every 6 months.
- Rinnai says to descale its tankless units at least once a year.
- ENERGY STAR notes heat pump water heaters may need annual maintenance, including air filter changes.
- Softened water speeds anode wear, so A. O. Smith calls for a yearly anode check on softened water.
- DOE and CPSC recommend a 120°F setting, which also slows mineral buildup.
- 6 monthsFirst drain, flush and anode check on an A. O. Smith gas tankA. O. Smith
- 5 yrsLongest gap between professional T&P valve inspectionsA. O. Smith
- 45–60 minCirculation time for a tankless descaleRinnai, Navien
- 18%Share of home energy used for water heatingDOE Energy Saver (archived)
| Heater type | Main yearly job | Other checks | Source |
|---|---|---|---|
| Gas or electric tank | Drain and flush | T&P lever test, anode check | A. O. Smith |
| Tankless (gas or electric) | Descale heat exchanger | Isolation valves, service alarms | Rinnai, Navien |
| Heat pump | Clean or change air filter | Condensate drain, tank flush | ENERGY STAR |
| Solar | Check by a solar contractor every 3–5 years | Fluid and descaling per system | DOE Energy Saver (archived) |
What water heater maintenance does a tank need?
A tank needs a drain and flush at least yearly, a T&P valve lever test at least yearly, and an anode check after the first six months (A. O. Smith's gas guide) or within three years at most (its electric instructions), then every year, or yearly from the start with softened water. DOE's older advice of every three to four years is looser than the makers'. Flushing clears sediment, the anode protects the steel from corrosion, and the relief valve is the safety device that keeps pressure and temperature in check. A. O. Smith adds a professional relief-valve and drain-line inspection no more than five years apart.
How is tankless water heater maintenance different?
Tankless water heater maintenance centers on descaling at least once a year, by circulating white vinegar or the maker's descaler through the heat exchanger for 45 to 60 minutes, according to Rinnai and Navien. Isolation valves with service ports make the job possible, and Rinnai's manual says scale damage isn't covered by warranty. Navien units show an E760 alarm when flushing service is due.
What maintenance does a heat pump water heater need?
A heat pump water heater needs the same tank care as any storage heater plus a clean air filter, since ENERGY STAR notes these units may need annual maintenance, including filter changes. The condensate line also has to keep draining; ENERGY STAR's install guide says the unit must sit level so condensate flows freely. Check the model's manual for its filter schedule.
How does hard water change water heater maintenance?
Hard water shortens the intervals: USGS says heated hard water leaves calcium carbonate scale, which means more tank sediment and faster tankless scaling. Testing hardness tells you whether yearly care is enough. A softener removes hardness but makes a tank's anode wear faster; salt-free conditioners don't remove hardness, and their scale claims come from the seller.
Which water heater maintenance jobs are DIY?
Flushing a tank, testing the T&P lever, setting the temperature and cleaning a heat pump filter are owner jobs in most manuals; gas, venting, 240 V wiring and valve replacement belong to a licensed pro. A. O. Smith's guide says to contact a qualified person if you can't do the routine tasks, if a drain valve won't open, or if a relief valve won't reseal. Its electric instructions warn to disconnect power before any service. Never cap, plug or remove a relief valve.
Sources and scope
This hub draws on two A. O. Smith tank manuals (gas, 2023; electric), Rinnai's flushing procedure and SENSEI RX manual, Navien's NPE operation manual, ENERGY STAR's heat pump water heater pages and 2024 install guide, USGS on water hardness, and archived DOE Energy Saver pages, each opened in October 2026. Each linked guide lists its own sources. Service plan pricing, contractor quotes and forum advice were left out.
Frequently asked
How often does a water heater need maintenance?
At least once a year for most types. A new A. O. Smith gas tank gets its first flush and anode check at six months, and hard water may call for more often.
What happens if you never maintain a water heater?
Sediment builds in tanks, scale builds in tankless heat exchangers, and anodes wear out unnoticed. Makers link that to lost hot water, noise, early leaks and denied warranty claims.
How do you test a T&P relief valve?
Stand clear of the discharge pipe, lift the lever briefly and let it snap back, per A. O. Smith. If it keeps running or won't reseal, shut off power or gas and the cold supply and call a qualified person.
Do electric water heaters need less maintenance than gas?
They skip the burner and venting checks gas units need, but the tank still needs flushing, anode checks and a relief valve test.
Is a water heater maintenance plan worth it?
That depends on the price and what it includes. Compare it with the jobs listed in your manual; most are yearly and short.
What maintenance does a solar water heater need?
DOE's archived guidance says simple systems may need service only every 3 to 5 years, preferably by a solar contractor, with glycol changes on that cycle.
Start over at the water heater type index