Why Is My Water Heater Making a Knocking/Rumbling Noise?

Does your water heater make a knocking/rumbling noise that could wake the dead?

If so, your water heater tank has most likely collected a thick layer of sediment (minerals like calcium and lime).

The solution: Drain the water heater tank and flush out the sediment. You can either flush it yourself or call a professional Atlanta-area plumber.

Here’s how sediment causes the noise

The sediment traps water underneath it at the bottom of the tank—where the gas heating burner is. When that gas burner heats the water, it boils and bubbles up until—BOOM—it escapes the sediment layer. This often sounds like a percolating coffee maker.

It’s just like if you had a water-filled covered pot on a hot stove. The stove would heat the water, causing it to bubble and push the lid up.

Is sediment buildup dangerous?

Well, your water heater won’t explode if that’s what you’re concerned about.

But sediment buildup can overheat the water heater’s tank, causing it to deteriorate. Just like how plaque deteriorates your teeth.

A deteriorated tank has a chance of leaking or bursting, causing costly water damage in your home. According to disastersafety.org, “Water heater failures cost an average of $4,444 per incident after the deductible was paid.”

Learn more in our article, “Should I Flush My Water Heater?” [FAQ]

How to drain and flush your water heater

Follow these instructions closely

1) Turn off the water heater.

a) For electric water heaters: turn off the water heater at the circuit breaker.
b) For gas water heaters: Turn the gas valve knob to pilot.

2) Turn the cold-water supply lever to a 90-degree angle

3) Connect a garden hose to the drain valve

4) Place the other end of the hose in an area (like a basement drain) where water can drain to and won’t be hurt by hot water.

5) Open a hot water spigot in the house to introduce air into the system. Otherwise, the water won’t come out of the hose.

6) Open the drain valve. Dirty water should start coming out of the hose.

7) Once the tank has completely drained, open and shut the cold-water supply valve a few times to flush out more sediment in the tank. Once you only see clear water, you’ve evacuated the sediment.

8) Close the drain valve; disconnect the hose from the valve.

9) Open the cold-water valve by turning the lever back in line with the cold water inlet pipe.

10) Close the hot water faucet you opened earlier once a steady stream of water flows and all of the air is purged out of the system.

11) Turn the water heater’s gas or power back on so it can start heating the water once all the air is fully purged out of the system.

12) Celebrate with a nice hot shower. You’re done!

Want a professional plumber’s help in Atlanta?

If the above sounds like too much work and you live in the Atlanta area, call Mr. Plumber to drain and flush your water heater.

We provide professional water heater and plumbing services to metro Atlanta including MariettaAlpharettaSuwaneeCantonWoodstockRoswellCumming, Lawrenceville, Douglasville, Newnan and more.

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