Your water heater needs about two hours of maintenance a year. That's it. Flush the tank once a year, test the temperature-and-pressure relief valve, and check the anode rod every two to three years. Those three tasks prevent the failures that kill most water heaters early: sediment damage, corrosion, and pressure problems.
Everything below is the complete list — what to do, how often, what's safe to do yourself, and what's a pro job.
Why Water Heater Maintenance Matters
A tank water heater is a steel tank holding 40 to 50 gallons of hot water under pressure, 24 hours a day. Sediment from the water supply settles on the bottom, the anode rod inside slowly sacrifices itself to corrosion, and every fitting ages. Neglect doesn't cause one dramatic failure — it causes three slow ones:
- Sediment buildup insulates the bottom of the tank from the burner or heating element, so the heater works harder, heats slower, and rumbles or pops. Over time it can overheat and weaken the tank.
- Corrosion eats the tank from the inside out once the anode rod is depleted. A corroded tank leaks — and a leaking tank gets replaced, not repaired.
- Pressure problems are what the T&P relief valve guards against. If that valve seizes shut and pressure spikes, the tank can fail catastrophically.
Most tank heaters last about 8 to 15 years. The ones that die at year 9 were usually never flushed. Regular maintenance pushes you toward the far end of that range, and it costs far less than early replacement. A professional maintenance visit — flush, valve test, and inspection — typically runs $75 to $250 in most markets; skipping it can cost you a $1,200+ replacement years early.
The Complete Water Heater Maintenance Checklist
| Task | How often | DIY or pro? |
|---|---|---|
| Flush the tank | Once a year (every 6 months if you have hard water) | DIY or pro |
| Test the T&P relief valve | Once a year | DIY |
| Check the anode rod | Every 2–3 years | Pro recommended |
| Set the thermostat to 120°F | Once a year | DIY |
| Look for leaks and corrosion | Every few months | DIY |
| Insulate hot water pipes | Once, then check yearly | DIY |
| Check gas venting (gas models) | Once a year | Pro during annual visit |
| Full professional inspection | Once a year | Pro |
How to Flush a Water Heater
Flushing is the single most important maintenance task. It removes the sediment that causes noise, inefficiency, and premature tank failure. It takes 30 to 60 minutes.
- Turn off the heater. Electric: switch the breaker off at the panel. Gas: turn the gas control valve to the "pilot" setting. Let the water cool for at least a couple of hours — drained water is scalding hot.
- Shut off the cold water supply at the valve on top of the heater.
- Attach a garden hose to the drain valve at the bottom of the tank. Run the other end to a floor drain, a utility sink, or outside — somewhere that handles hot, sediment-laden water.
- Open the T&P relief valve briefly (lift the lever) to let air into the tank, which helps the water flow out. Then open the drain valve.
- Drain until the water runs clear. The first few gallons will look sandy or brown — that's the sediment you're removing. If you want a deeper clean, turn the cold water back on briefly to stir up the bottom and drain again until clear.
- Close everything and refill. Close the drain valve and the T&P valve, reopen the cold water supply, and open a hot faucet somewhere in the house to bleed trapped air. When water flows steadily, close the faucet.
- Turn the heater back on and check around the drain valve for drips.
Two cautions: never let the drain valve's plastic handle crack — they can seize on old units, and if yours won't budge, that's a sign of heavy buildup and a good reason to schedule a tank flush and sediment cleaning with a pro. And on electric models, never restore power while the tank is empty — a "dry-fired" heating element burns out in seconds.
Test the Temperature & Pressure Relief Valve
The T&P valve is the safety device on the side or top of your tank. If pressure or temperature climbs dangerously, it opens and vents water. Test it once a year:
- Lift the lever briefly, then release it. You should hear a burst of water into the discharge pipe, and it should stop completely when you let go.
- If nothing comes out, or it keeps dripping afterward, the valve needs replacing — this is a safety issue, not a cosmetic one, so don't postpone it.
Check the Anode Rod
The anode rod is a magnesium or aluminum rod threaded into the top of the tank. It corrodes on purpose — sacrificing itself so the steel tank doesn't rust. Check it every 2 to 3 years; replace it when it's visibly eaten away, coated in calcium, or worn down to a thin wire.
This is the one task most guides underplay, because a fresh anode rod can add years to a tank's life — it's the cheapest life-extension money you can spend on a water heater. It's often best left to a pro: the rod can be tightly seized, and forcing it risks damaging the tank. If your hot water smells metallic or looks rusty, the rod is likely already depleted and the tank may be starting to corrode.
Set the Temperature to 120°F
The U.S. Department of Energy recommends 120°F as the standard setting, and for good reasons: hotter water wastes energy, accelerates sediment buildup, and creates a scalding risk — especially for children and older adults. Check the setting once a year; dials get bumped.
If the temperature keeps drifting or one faucet is scalding while another is lukewarm, the thermostat itself may be failing. See our thermostat replacement page for what's involved.
Look for Leaks and Corrosion
Every few months, take two minutes around the tank. Check:
- The base of the tank and the drain valve for moisture
- Pipe fittings at the top for slow drips
- The outside of the tank for rust spots or blistering paint
- The discharge pipe under the T&P valve for signs it has been venting water
Catch a fitting drip early and it's a cheap fix. Catch it late — or find a tank that's rusting through — and you're reading our water heater replacement guide instead. If you're not sure what you're looking at, our leak detection service covers a proper diagnosis.
Insulate Pipes (and the Tank)
Wrapping the first few feet of hot-water pipe with foam insulation sleeves cuts heat loss and shortens the wait for hot water at the tap. On older tanks without built-in insulation, a water heater blanket helps too — just keep it clear of the burner area and controls on gas models. This is a one-time job; check it yearly for slipping or damage.
Gas Heater Extra: Check the Vent
If your heater is gas, the vent pipe that carries exhaust gases out of the house must be intact, correctly sloped, and free of obstructions. A quick look once a year is fine for spotting obvious problems — rusted sections, a disconnected joint, or a blocked termination. Anything beyond that belongs in the annual professional visit; combustion safety isn't a DIY experiment.
When to Call a Professional
Some maintenance is fine on a Saturday afternoon. This isn't:
- Anything involving gas — gas valves, pilot assemblies, burners. Gas work needs a licensed technician, full stop.
- Anode rod replacement — seized rods and tank threads need the right tools and judgment.
- A T&P valve that fails its test — or a discharge pipe that's wet, which means the valve has been opening under pressure.
- A drain valve that won't open or won't seal — forcing it can crack the fitting and flood the area.
- Rust on the tank itself, metallic-smelling water, or rumbling that flushing doesn't fix.
An annual professional water heater maintenance visit covers all of this: flush, valve test, anode check, thermostat verification, and venting inspection. It's the cheapest hour of labor you'll ever buy for your plumbing.
Tankless Water Heaters: What's Different
Tankless units don't store water, so there's no tank to flush — but they need an annual descaling with a vinegar or descaling solution to clear mineral buildup from the heat exchanger, plus periodic filter cleaning and a check for error codes. The process is different enough to deserve its own guide, so treat this article as the tank-style playbook.
What Happens If You Skip Maintenance
Nothing, for a while — and then everything at once. Sediment bakes into a crust that overheats the tank floor, the anode rod disappears and the tank starts rusting, and a stuck T&P valve quietly removes your safety margin. The endpoint is the classic story: a tank that leaks at 2 a.m., a water heater repair that costs more than the heater is worth, or a full replacement five years early. If you're already seeing signs your water heater is failing — rumbling, rusty water, or moisture around the base — maintenance has already become repair. Book the visit.