Water heater maintenance is unglamorous but pays back at a 10:1 ratio in extended lifespan and avoided repair calls. The average US water heater goes its entire service life without a single maintenance event — and dies at year 8-10 instead of year 14-18. One hour a year keeps it inside warranty and at rated efficiency.
Annual checklist — tank water heaters (gas or electric)
- Test the pressure relief (T&P) valve. Lift the handle for 2 seconds; water should discharge through the drain tube. Reseat. If it dribbles continuously after, replace the valve ($15-40 part)
- Flush the tank to remove sediment. See our how to flush a water heater guide. 30-60 minutes; removes 1-3 gallons of cooked mineral sludge in hard-water regions
- Check the anode rod. Unscrew the hex head on top of the tank; pull the rod. If it's down to bare core wire (less than ½" of magnesium/aluminum left) or coated in calcium, replace ($30-50 part). This is the single highest-ROI maintenance task
- Inspect for leaks. Top fittings, T&P discharge, drain valve, around the base
- Check the burner area (gas). Vacuum dust and lint from the air intake screen — required on Bradford White Defender / ICON units, helpful on all gas tanks
- Verify temperature setting — should be at 120°F unless a specific use case forces higher
- Inspect venting (gas) — for atmospheric units, verify draft (smoke pencil or smell test for spillage at the draft hood)
Annual checklist — tankless water heaters
- Descale the heat exchanger. 60-90 min job with a $40 pump kit. Annual in hard water (>11 gpg), every 2 years in soft water. The single most important tankless maintenance task. See brand-specific guides: Rinnai, Navien, Rheem
- Clean the inlet water filter. Small screen at the cold inlet. Removes sediment before scale forms
- Clean the air inlet filter. Base of the unit. Lint and pet hair restrict combustion air
- Inspect the vent termination. Clear of leaves, ice, or insect nests
- Inspect the condensate trap and drain (condensing models). Clear any sediment; verify free flow
- Test the pressure relief valve if installed inline
- Verify gas pressure — every 2-3 years. Requires a manometer; have a plumber do this
- Update controller firmware via the manufacturer's app (NaviLink, ControlR, EcoNet)
Annual checklist — heat pump / hybrid
- All annual tank tasks from above (test T&P, flush sediment, check anode rod, inspect leaks)
- Clean the evaporator coil and air filter on top of the unit. Vacuum dust accumulation
- Verify clearances around the unit — heat pumps need at least 750 cubic feet of unconditioned air space to operate efficiently in heat pump mode
- Clean the condensate drain pan — heat pumps produce condensate similar to AC units
- Check refrigerant lines for visible damage (rare)
How often does each task need to happen?
| Task | Soft water (<7 gpg) | Hard water (>11 gpg) |
|---|---|---|
| Test T&P valve | Annually | Annually |
| Flush tank (tanks) | Every 2 years | Annually |
| Check anode rod | Year 3, then every 2 years | Year 2, then annually |
| Descale heat exchanger (tankless) | Every 2 years | Annually |
| Replace anode rod | Every 5-7 years | Every 3-4 years |
| Vacuum air intake (gas) | Annually | Annually |
| Heat pump evaporator clean | Annually | Annually |
DIY vs annual service contract
Most maintenance is DIY-friendly — flush, anode rod, T&P test, filter cleaning. Total tool cost under $100 (element wrench, pump kit, garden hose).
Reasons to pay $150-300/year for a maintenance contract instead:
- You're not comfortable working with gas or electric appliances
- Tankless + hard water + you'll forget annually
- The contract bundles annual maintenance with priority service-call response
- Documented maintenance helps warranty claims
Maintenance and warranty
Most water heater warranties require "reasonable maintenance" — vague language that becomes specific when a claim is filed. If a heat exchanger fails and the inspector finds heavy scale, the claim is denied. Keep maintenance documentation: dated photos of the bucket of descaling fluid, receipts for anode rod replacements, service records. This becomes warranty defense if needed.
What happens if you skip maintenance?
- Tank water heater (skipping flushes): sediment cooks at the bottom, insulates the burner from the water. Lower efficiency, then popping noises, then bottom-tank corrosion. Lifespan drops from 12-14 years to 7-9
- Tank water heater (skipping anode rod replacement): rod consumed by year 5-6; from then on the tank shell corrodes. Lifespan drops from 14-18 years to 8-10
- Tankless (skipping descales): heat exchanger scales, output drops 15-30%, then overheats and trips Code 14 / 016. If ignored: heat exchanger permanent damage, $1,000+ repair
- Heat pump (skipping coil cleaning): efficiency drops 10-25%; energy bill rises
Brand-specific maintenance guides
- Rheem maintenance
- AO Smith maintenance
- Bradford White maintenance (intake filter specific)
- Rinnai maintenance
- Navien maintenance
Bottom line
One Saturday morning per year keeps a water heater at rated efficiency and lifespan. For tank: flush + anode rod + T&P test. For tankless: descale + filter cleaning. Document it. The maintenance you do this year is the difference between a year-14 replacement and a year-9 replacement.