Drain sediment from a tank water heater
Sediment settles at the bottom of a tank water heater and makes it work harder. Draining a little water clears some of it. A full flush is a bigger job that many people hand to a plumber.
Last reviewed against 3 official sources.
Who this is for
People with a tank (storage) water heater that is in good shape and has a drain valve they can reach. Tankless heaters are different: follow the maker’s descaling instructions.
How often should I flush my water heater?
The U.S. Department of Energy says to drain a quart of water from the tank every 3 months to remove sediment, following the manufacturer’s directions. Rheem, one water heater maker, suggests a full flush once a year, or every 6 months with hard water. Your own heater’s manual decides.
From: U.S. Department of Energy; Rheem Manufacturing Company
What you need
Tools
- Bucket
- Garden hose (for a full flush)
- Work gloves
Supplies
- Your water heater’s manual
Steps
- Read your manual firstIt tells you where the drain valve is and whether the maker wants the power or gas off for this job.
- Put a bucket under the drain valveThe valve is near the bottom of the tank. The water will be hot.
- Drain about a quartOpen the valve slowly, let roughly a quart run into the bucket, then close the valve firmly.
- Look at the water and the valveA little grit is normal. Watch the valve for a minute to be sure it has stopped dripping.
- Decide whether a full flush is neededRheem lists rumbling or popping noises, rusty or cloudy hot water, and running out of hot water sooner than usual as signs of sediment.
- For a full flush, follow the maker’s orderRheem’s outline: turn off the electricity or gas and the cold water inlet, run a hose from the drain valve to a place hot water will not harm, drain the tank, close the valve, then refill with hot taps open.
- Restore power or gas lastTurn the electricity or gas back on only after water flows steadily from the hot taps.
Safety notes
- The water can scald. Keep children and pets away and wear gloves.
- The Department of Energy suggests setting the heater to 120°F, a temperature it describes as safe for most people.
- Keep the burner access door on a gas water heater closed, and keep anything that can burn at least 3 feet away.
- If you smell gas, leave the home and call your gas company from outside.
When to call a professional
- Rheem says to call a professional if the drain valve will not open or leaks, if there is heavy rust or corrosion around the fittings, or if the noise continues after flushing.
- Call one too if the heater is 8 to 12 years old or older, or if you are unsure about its gas or electrical parts. Hardened sediment in an old tank can need special tools.
- Gas lines, burners, venting and wiring are professional-only work.
Sources
- Energy Saver: Tips on Saving Money and Energy in Your Home (PDF) (opens in a new tab)U.S. Department of Energy · Government
- How Often To Flush Your Water Heater (And How To Do It) (opens in a new tab)Rheem Manufacturing Company · Manufacturer
- Basement and Garage Fire Safety (opens in a new tab)U.S. Fire Administration (FEMA) · Government
This guide is general information written in our own words from the sources above. Your owner’s manual and the instructions for your own equipment come first.
Tell it once. It remembers.
Drain about a quart every 3 months; your heater’s manual decides.