How to Flush a Tank Water Heater

Flushing a tank removes sediment that reduces efficiency.

Grit and minerals slowly pile up on a storage tank floor. Under a gas burner that layer traps heat and pops and rumbles; in an electric unit it can smother the bottom element. Flushing once a year reduces both problems.

Before you start, turn off gas or power, close the cold supply, and let the water cool for a few hours to avoid scalding. Run a garden hose from the tank drain cock over to the basement grate. Next, open a hot faucet on the floor above so air can enter, then open the spigot. Briefly open the cold supply to stir sediment, then close it again.

When the water runs clear, close the drain, refill the tank with a hot tap open until water flows, then restore power or relight. Rental tanks are usually maintained by the provider.

1. Turn off gas or power
2. Close the cold supply
3. Attach a hose to the drain valve
4. Open a hot tap and drain
5. Refill before restoring heat

• Garden hose
• Bucket
• Screwdriver

1. 01

   Set the gas valve to pilot or switch off the breaker

2. 02

   Close the cold water supply

3. 03

   Thread a garden hose onto the tank drain cock and lead it to the floor drain

4. 04

   Open the drain valve and a hot tap upstairs

5. 05

   Flush until the water runs clear, then refill before turning heat back on

Flushing removes sediment that makes the heater rumble and work harder.

Whitby Plumbing, from the job

• The drain valve will not open
• The valve leaks after flushing
• The tank is very old

Ring the desk if the drain valve leaks or will not open.

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