How to flush a water heater, and why hard water makes it matter

What the sediment does

Scale builds a layer on the bottom of the tank, between the burner and the water. The heater runs longer to do the same job, the bottom of the tank overheats, and you hear popping or rumbling as water boils up through the sediment. Left alone, it is one of the main reasons tanks here fail early.

How to flush it

Give yourself about an hour. You need a garden hose.

• Gas heater: turn the control knob to pilot or vacation. Electric heater: switch off its breaker.
• Close the cold water valve on the pipe above the heater.
• Connect a garden hose to the drain valve at the bottom and run it to a driveway or drain. The water will be hot.
• Open a hot faucet somewhere in the house so air can get in.
• Open the drain valve and let the tank empty.
• Open the cold water valve for short bursts to stir up the sediment. Repeat until the water from the hose runs clear.
• Close the drain valve, take off the hose, and open the cold water valve to refill.
• When water runs steady from the open hot faucet, the tank is full. Close the faucet, then turn the gas back up or the breaker back on.

Never heat an empty tank

Do not turn the gas up or the breaker on until the tank is full. An electric element that fires dry burns out in seconds.

When to leave it alone

If the heater is ten years old or more and has never been flushed, think twice. The drain valve can clog with sediment and refuse to close, and on a badly corroded tank the scale may be the only thing covering a weak spot. On an old tank, call first and describe it.

Signs it is past flushing

• Water pooling under the tank
• Rust-colored hot water
• Rumbling that comes back right after a flush
• Hot water that runs out much faster than it used to

If you would rather not do it yourself

Call Mickey. He will tell you on the phone whether the heater is worth flushing, repairing, or replacing, and what each would cost. The estimate is free, and most replacements in La Mirada are done the same day.