Water heater maintenance guide
A little maintenance each year keeps a water heater running longer and cheaper. Flushing sediment, testing the relief valve and checking the anode rod take about an hour. Here is what to do, how often, and what a plumber charges if you would rather not.
What maintenance costs
$75 – $250professional tank flush
A professional flush costs $75 to $250. A full tune-up with inspection, anode check and valve test runs $100 to $500. Tankless descaling costs $75 to $300. Doing it yourself costs almost nothing.
Maintenance schedule and costs
| Task | How often | Pro cost |
|---|---|---|
| Test the pressure relief (T&P) valve | Once a year | Included in tune-up |
| Flush sediment from the tank | Once a year | $75 – $250 |
| Inspect the anode rod | Every 2–3 years | Included in tune-up |
| Replace the anode rod | When half worn | $150 – $350 |
| Descale a tankless heater | Once a year | $75 – $300 |
| Full tune-up | Every 1–2 years | $100 – $500 |
How to flush a tank water heater
- Turn the thermostat to pilot or vacation (gas), or switch off the breaker (electric).
- Close the cold water supply valve on top of the tank.
- Attach a garden hose to the drain valve and run it to a floor drain or outside.
- Open a hot water faucet in the house to let air in.
- Open the drain valve and let the tank empty. Briefly reopen the cold supply to stir up remaining sediment.
- Close the drain valve, open the cold supply, and wait until water flows steadily from the open faucet.
- Restore gas or power only after the tank is full.
Water in the tank can be hot enough to scald. Let it cool for a few hours or wear gloves, and never turn on an electric element with an empty tank.
How to descale a tankless water heater
Shut off power or gas and the water valves, connect a small pump and hoses to the service valves, and circulate a descaling solution or white vinegar through the unit for about an hour. Rinse with clean water and clean the inlet filter. Follow your manufacturer's manual; some require specific solutions.
Why maintenance saves money
- Sediment makes the heater work harder and can cause early tank failure.
- A worn anode rod lets the tank rust from the inside; a $150 to $350 rod can add years to a tank.
- A stuck relief valve is a safety hazard.
- Many manufacturer warranties require proof of regular maintenance.
What plumbers charge for this job
Most of the price of a plumbing job is labor. Licensed plumbers in the U.S. typically charge $45 to $150 per hour, and many add a $50 to $200 service call fee that often covers the first hour. Expect evening, weekend and holiday visits to cost noticeably more; emergency hourly rates commonly run $150 to $350. Master plumbers and plumbers in high-cost metro areas sit at the top of these ranges.
Before work starts, ask whether the quote is a flat price for the whole job or an hourly estimate, and whether parts, permits and haul-away are included. See Plumber rates per hour and Emergency plumber cost for the full breakdown.
When to call a plumber
Call a plumber if the drain valve will not open or leaks, the relief valve drips after testing, water is rusty after a flush, or you smell gas. Repair prices are in Water heater repair cost.
Frequently asked questions
How often should I flush my water heater?
Once a year for most homes, and every six months if you have hard water.
How much does it cost to flush a water heater?
A plumber typically charges $75 to $250. Doing it yourself needs only a garden hose.
What happens if you never flush your water heater?
Sediment builds up, efficiency drops, the tank can make popping noises, and the bottom can overheat and fail early.
Do tankless water heaters need maintenance?
Yes. They need yearly descaling and inlet filter cleaning to prevent mineral buildup in the heat exchanger.
Sources
Prices are national estimates for 2026 based on published cost surveys and labor data. Your local price can be higher or lower. FairFix Costs is not a plumbing contractor; read our disclaimer.