Water Heater Making Rumbling or Popping Noise? What It Means
A noisy water heater is not about to explode. But it is telling you something important. Here is what the sounds mean.
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What Causes the Noise
Sediment from your water supply settles at the bottom of the tank over time. When the burner heats the water, trapped water under the sediment turns to steam and bursts through the sediment layer, causing popping and rumbling sounds. The more sediment, the louder the noise. This is not dangerous or a sign of imminent failure, but it does reduce heating efficiency and can shorten the lifespan of your water heater.
How to Flush the Sediment
Turn off the water heater (gas: set to pilot; electric: flip the breaker). Connect a garden hose to the drain valve at the bottom of the tank and run it to a floor drain or outside. Open the drain valve and let water flow until it runs clear, usually 5 to 10 minutes. Close the drain valve, remove the hose, and turn the water heater back on. This takes about 20 minutes and should be done annually.
Other Sounds and What They Mean
Hissing: usually condensation dripping onto the hot burner, which is normal during heating cycles. Knocking or hammering: likely water hammer from your pipes, not the heater itself. Install water hammer arrestors on nearby supply lines. Screeching or high-pitched whine: a partially closed valve restricting water flow. Check the inlet and outlet valves and open them fully. Ticking: the heat trap nipples expanding and contracting, which is normal and harmless.
When to Call a Professional
Call a plumber if the noise continues after flushing, if you notice rusty water coming from hot taps (the tank may be corroding from inside), if the water heater is more than 10 to 12 years old and making new noises (it may be near end of life), or if you see water pooling around the base of the heater (the tank may be leaking). A water heater replacement costs 800 to 1,500 dollars including installation.
