Popping Sound Coming from Water Heater? Here’s Why (and How to Fix It)

Do you hear what sounds like popcorn popping whenever your water heater heats the water like the guy in this video?

The problem is sediment buildup on the bottom of your water heater tank. Don’t let this continue, or you’ll shorten the life of your water heater.

You need to flush your water heater (more on that later), but first let’s look at why this noise is happening in the first place and why it’s bad.

Why sediment causes the popping sound

Under the layer of sediment at the bottom of your tank is some trapped water. As the water is heated, it bubbles up through the sediment, creating a popping sound.

“But how’d sediment get in there?”

The tap water in Minnesota is hard—that is, it has many dissolved minerals in it. The minerals are safe to drink; your body actually needs some of these minerals.

But the minerals are bad news for your tank. They “un-dissolve” out of the water and settle at the bottom of the tank. Over time, this creates a layer of sediment on the bottom of the tank. Which creates some problems...

Why sediment buildup is bad

The layer of sediment on the bottom of your water heater tank creates several problems:

  • Makes the water heater less efficient. Your water heater’s burner is at the bottom. A layer of sediment blocks the heat, causing your water heater to work harder to heat your water.
  • Shrinks the water heater’s capacity. The layer of sediment can take up a good amount of space, leaving you with less hot water for your home.
  • Damages the water heater tank. Since it slows the transfer of heat to the water, it can cause the tank to overheat, which can damage the tank and lead to a leak.

How to fix it

Your water heater needs to be completely flushed to remove the sediment. Flushing involves emptying the water heater tank of water and flushing some clean water through it.

Manufacturers recommend this is done yearly to increase the life of your water heater.

You can have a professional take care of this maintenance for you or you can do it yourself (instructions are below.) 

How to flush your water heater

You first want to drain the water heater:

1. Turn off the water heater.

2. Turn off the cold water into the water heater.

Cold water inlet valve for water heater.

3. Connect a hose to the drain valve at the bottom of the water heater.

Drain valve on bottom of water heater tank.


4. Place the other end of the hose somewhere that the water can drain.

5. Open the drain valve. 

Dirty water should now be flowing out of the hose. It will be hot, so be careful. 

In some cases, sediment may actually block the drain, preventing you from draining the water heater. Or the drain valve may crack when you try to open it. If this happens, contact a professional plumber for help repairing your water heater.

Once the water heater is completely drained, it’s time to flush and refill it. Here’s how to do that:

  1. Turn on the cold water supply going into the water heater tank.
  2. Watch the water coming out of the hose. You’ll know you’re done when the water is clear.
  3. Close the drain valve.
  4. Disconnect the hose from the valve.
  5. Make sure the cold water supply is all the way on and wait about 10 minutes for the water to fill the tank.
  6. Turn on a water heater faucet to remove any air from the tank, then turn it off.
  7. Turn the water heater back on.

Benjamin Franklin Plumbing serves Hastings, MN and the surrounding cities, including Apple Valley, Burnsville, Cottage Grove, Eagan, Woodbury, Lakeville, Rosemount and Stillwater. Contact us for more information.

Share |
View by Month

View by Category