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Thump, It’s the Water Heater

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Water Heater Making Noise

It’s annoying when your water heater thumps, pops, and whomps whenever you use hot water. What can you do?

You’ve probably heard your water heater thumping, popping or even hissing when you turn on the tap. This is a fairly common problem that has many causes and solutions. The most common cause of this issue is excess sediment in hard water. A buildup of sediment can be the result of several factors, including the local water supply.

The water heater’s thumping is caused by sediment that has built up in the bottom of the metal tank or around the electrical heating elements. The illustration shows a gas water heater with this problem. The sediment interferes with even heat transfer and allows steam bubbles to form. The bubbles float upward and then implode with a muffled thump.

Water Heater Making Noise

The easiest way to reduce the sediment-caused thumping noises your water heater makes is to put a water filter in the sink and have it hooked up to your cold water line. This should solve both your sediment problems and save you some money on water.

You could try to drain sediment from the bottom of the tank. Attach a hose to the drain valve and route it to a safe plumbing fixture, such as a floor drain. Be careful; the water will be hot. Drain a few gallons; repeat this several times. Often, though, sediment is challenging to remove from the tank.

The thumping does not cause any damage to the water heater, but it certainly is annoying. Consider installing a water softener to eliminate the hard water sediment.