Most homeowners never touch their water heater until it stops working. The problem is, skipping maintenance cuts the unit's lifespan from 12 -- 15 years down to 7 -- 9 years. A few simple tasks once a year can save you $1,000 -- $2,500 in premature replacement costs.

The Annual Water Heater Maintenance Checklist

Do these tasks once a year -- twice if you have hard water:

Flush the tank to remove sediment buildup
Test the T&P relief valve to confirm it opens and closes properly
Inspect the anode rod and replace if less than 1/2 inch thick or heavily corroded
Verify thermostat is set to 120°F -- not higher
Check for leaks around the base, connections, and pressure relief line
Inspect venting (gas heaters) for blockage or back-drafting
Clean air intake vents on gas models to prevent combustion issues

Most of this takes 15 -- 30 minutes. The tank flush takes longer -- about 30 -- 60 minutes -- but it's the most important step.

Step 1: Flush the Tank

Sediment builds up at the bottom of every tank water heater. Over time it insulates the water from the heating element, forces the burner to run longer, and adds to your energy bill. Heavy sediment also causes that banging and rumbling sound when the heater runs.

How to flush your tank:

Turn the thermostat to "pilot" (gas) or switch off the breaker (electric).
Connect a garden hose to the drain valve at the bottom of the tank.
Run the hose to a floor drain or outside -- water will be hot.
Open a hot water faucet somewhere in the house to prevent a vacuum lock.
Open the drain valve and let the tank drain until the water runs clear. That usually takes 5 -- 15 minutes.
Close the drain valve, disconnect the hose, let the tank refill fully, then restore power.

If you have hard water, flush every 6 months. Hard water deposits sediment faster and shortens tank life significantly. Signs you're overdue: rumbling or popping sounds during heating cycles, or longer-than-usual wait for hot water.

Step 2: Test the T&P Relief Valve

The temperature and pressure relief valve is a safety device. If water pressure or temperature gets dangerously high, it opens automatically to prevent an explosion. A stuck or failed T&P valve is a serious hazard.

Here's how to test it:

Locate the T&P valve on the side or top of the tank. A discharge pipe runs down from it to the floor.
Place a bucket under the discharge pipe end.
Lift the lever briefly -- just 2 -- 3 seconds. Water should flow out and stop cleanly when you release it.
If it doesn't release water, or if it keeps dripping after you let go, replace the valve. The part costs $20 -- $50. A plumber charges $100 -- $250 to replace it.

A T&P valve that won't seal after testing is a common problem on older heaters. Don't ignore it -- a failed T&P valve turns a routine maintenance issue into a potential emergency.

Step 3: Check the Anode Rod

The anode rod is a metal rod inside the tank that corrodes so the tank doesn't. It's called a sacrificial anode -- it takes the hit so your tank walls stay intact. Once the rod is fully consumed, the tank starts to rust from the inside.

How to inspect it:

Find the anode rod port on the top of the tank -- usually under a plastic cap marked "anode."
Use a 1-1/16 inch socket and breaker bar to remove it. Apply thread sealant tape on reinstallation.
Replace the rod if it's less than 1/2 inch thick, covered in heavy calcium deposits, or more than 6 inches of core wire is exposed.
New anode rods cost $20 -- $50 for magnesium or aluminum types. Replacing one yourself takes about 30 minutes.

Most anode rods last 3 -- 5 years. If you have a water softener, check annually -- softened water depletes anode rods faster. Skipping this step lets the tank rust internally, which typically means a $1,200 -- $4,500 replacement.

Step 4: Temperature and Insulation Check

Your water heater thermostat should be set to 120°F. That's hot enough to kill Legionella bacteria but low enough to prevent scalding. Temperatures above 120°F increase energy costs by roughly 4 -- 22% for every 10°F above that threshold.

Two quick additions that cut energy waste:

Pipe insulation: Wrap the first 6 feet of hot water pipe leaving the heater with foam pipe insulation ($10 -- $20 at any hardware store). Reduces standby heat loss.
Tank blanket: If your heater is in an unheated garage or basement, an insulating blanket ($20 -- $40) saves 7 -- 16% on heating costs. Skip this on newer heaters -- they're already insulated at the factory.

Tank vs. Tankless: Different Maintenance Needs

Tankless water heaters don't store water so there's no sediment flush, but they need descaling -- especially in hard water areas.

Tank water heaters: Flush annually, check anode rod annually, test T&P valve annually. Life expectancy 10 -- 15 years with maintenance.
Tankless water heaters: Descale once a year by flushing white vinegar solution through the heat exchanger. Clean the inlet filter screen. Inspect the venting system for blockage. Life expectancy 15 -- 20 years with maintenance.

Professional tankless maintenance costs $100 -- $200 per year. Doing it yourself runs $20 -- $30 in supplies and takes 2 -- 3 hours with the right descaling kit. If you need a plumber for tankless service, expect $75 -- $150/hr plus parts.

When to Call a Plumber

Some things are easy DIY. These are not -- call a plumber if you see:

Rust-colored water from the hot tap. That's internal tank corrosion. Usually means replacement is coming.
Water pooling at the base. Likely a failed pressure relief valve or tank leak.
No hot water or inconsistent temperature. Thermostat or heating element failure on electric units; pilot light or gas valve issue on gas units.
T&P valve opens repeatedly. A pressure problem in the system that needs diagnosis -- not just a valve swap.
Rotten egg smell from hot water. Sulfur-reducing bacteria in the tank. Needs a chlorination flush and anode rod replacement with an aluminum-zinc rod.

Plumbers charge $75 -- $200/hr for water heater service. Most diagnostic visits take under an hour. If your unit is over 10 years old and showing problems, see our water heater replacement cost guide before investing in repairs.

For Plumbers: Turn This Into a Maintenance Plan

Annual water heater maintenance is a natural recurring revenue add-on for plumbing businesses. A semi-annual plan -- one spring check and one fall check -- runs $150 -- $300/year per customer and takes about 45 -- 60 minutes per visit.

What to include in a plumbing maintenance plan visit:

Flush the tank and inspect drain valve condition
Test T&P valve and discharge pipe
Inspect anode rod (replace if needed, billable separately)
Check thermostat setting and heating element function
Inspect for leaks at connections and valves
Check gas line connections and burner flame color (gas units)

Customers on maintenance plans renew at much higher rates than one-time service calls. See our guide on building a plumbing maintenance plan business for the full pricing and conversion strategy.

Bottom Line

Annual water heater maintenance takes about an hour and costs almost nothing DIY. Flush the tank, test the T&P valve, check the anode rod, and set the temperature to 120°F. Skipping these tasks turns a 15-year appliance into a 9-year one -- costing you $1,200 -- $4,500 in premature replacement.

If you're a plumber offering maintenance plans, try QuoteSnap for free. Customers can get instant maintenance plan pricing right on your website -- no back-and-forth, no missed leads.

Plumbing Water Heater Maintenance: Annual Checklist for Homeowners (2026)