Short answer
If your water heater pops or rumbles, turn it off and let the water cool for several hours. Then drain a few gallons from the drain valve into a bucket until it runs clear. The noise usually means sediment, minerals from hard water, at the bottom of the tank: water trapped under it boils and pops. It is not dangerous by itself, but it wastes energy. On an old tank, ask a plumber first.
Safety first
The water in the tank can be hot enough to burn you: turn the heater off and let it cool for several hours before you open the drain valve. Gas smell? Get out and call 911 or the gas company from outside. On an electric heater, switch off its breaker before draining and do not turn it back on until the tank is full.
How to stop a water heater from popping
1Popping and rumbling from the tank
The noise comes from the bottom, mostly while the burner or the elements are heating. It is a warning sign, not an emergency.
Read all the steps
- Popping and rumbling from the tank. The noise comes from the bottom, mostly while the burner or the elements are heating. It is a warning sign, not an emergency.
- Sediment on the bottom is the cause. Minerals from the water settle in a layer. Water trapped under it boils in little bursts: that is the popping you hear.
- Turn it off and let it cool for hours. Gas: knob to OFF or PILOT. Electric: switch off its breaker. Wait several hours, or overnight, so the water cannot scald you.
- Tank cool? Drain into a bucket. Attach a garden hose to the drain valve and run it to a floor drain, outside or into a bucket. Open the valve until the water runs clear.
- Close it, refill, then turn it on. Close the drain valve and let the tank fill. Open a hot faucet until water flows steadily, then turn the gas or the breaker back on.
- Still not fixed? Call a plumber Especially if: the noise stays loud after you flush the tank.
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If the drain valve leaks or will not open
On an older tank that was never flushed, the drain valve can clog with sediment or start dripping after you open it. Close it snugly by hand. If it keeps dripping, put a bucket under it and call a plumber: it is a simple part to replace.
How often to flush
Many manufacturers suggest flushing once a year, and more often with hard water. Check the manual for your model. If the popping started after years without a flush, a plumber can flush the tank fully and check the anode rod at the same visit.
What not to do
- Do not open the drain valve on a hot tank. Let it cool first.
- Do not turn on an electric heater while the tank is empty or partly full: the elements burn out almost right away.
- Do not use the relief valve to drain the tank. It is a safety valve, not a faucet.
- Do not ignore loud banging together with water at the base: the tank may be failing.
When to call a plumber
- The noise stays loud after you flush the tank.
- Water leaks from the base of the tank or from the drain valve.
- The heater is old and has never been flushed (the drain valve may not seal again).
- You also have rusty hot water, or the hot water runs out fast.
Frequently asked questions
Is a popping water heater dangerous?
Not by itself. It usually means sediment at the bottom of the tank. But it wastes energy and can shorten the life of the heater, and loud banging with a leak means the tank may be failing.
How do I stop my water heater from making popping noises?
Flush out the sediment. Turn the heater off, let it cool, drain water from the drain valve until it runs clear, refill the tank, then turn it back on.
How often should I flush my water heater?
Many manufacturers suggest once a year, and more often with hard water. Check the manual for your model.
Can I flush a water heater myself?
Yes, if the tank is cool and the drain valve works. On an old tank that was never flushed, the valve may clog or leak, so a plumber is the safer choice.
Why does my electric water heater make a sizzling sound?
Sediment or scale on the heating elements makes them sizzle or hiss while they heat. Flushing helps. If you hear sizzling and see water leaking, switch off its breaker and call.