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No, Your Water Heater Shouldn’t Be Making That Noise

Shocked and surprised“Knock-Knock-Knock”

No, unfortunately this is not the beginning of a funny joke. It’s an indication of a problem with your water heater, though, if that’s where it’s coming from.

A tank water heater system may occasionally make this noise, and while sometimes it may be the symptom of something fairly benign that just requires a “quick” fix, other times it can be more serious. The fact is though, no sound coming from your water heater or any other home appliance should be ignored. A knocking noise very often indicates a problem that can only grow larger the longer you neglect it.

Keep reading to learn about a possible reason for this sound and what you should do about it.


The knocking noise you hear coming from your water heater is very likely due to mineral deposits, or sediment, that’s gathered at the bottom of the water heater tank. This is also known as scale or more familiarly, limescale.

What happens is that there is a reduced volume in the tank, and the sound occurs when steam bubbles are forced to the top of the water heater tank as the burners heat up. The bubbles get trapped, and they rattle the sediment around at the bottom of the tank. This causes knocking, popping, or even rattling.

We’ve found other potential sources that can be described as knocking as well, so we don’t want you to assume anything or try to resolve the problem on your own. The best thing you can do is to call in our highly trained and experienced professional plumbers. Scaling can cause major damage to a tank, such as corrosion, so don’t hesitate to contact us if you suspect something is up with your water heater.

How Does Scale Get in a Water Heater Tank?

So, how does scaling get into the water heater tank to begin with? Well, it’s the result of hard water already in your plumbing system. Hard water is that with a high concentration of minerals—namely magnesium and calcium. These are harmless to ingest for people and pets, however over time, they can cause some damage to your pipes and plumbing components.

Deposits get left behind in the bottom of your water heater tank, which is made of metal but lined with glass. The deposits rattle around at the bottom of the tank, and can wear down this lining as a result, which will cause the tank to start corroding. Once this occurs, you’ll have no choice but to replace the system.

Flushing Your Water Heater

If you aren’t able to have a water softener installed or for whatever reason you’ll always be dealing with hard water, there is still a way to regularly clear out the sediment in the tank. You may go online and see many online videos on doing such a job. But honestly, unless you are a water heater professional yourself, it’s best to call in our team.

Call the friendly team at Admiral Plumbing Services, LLC for exceptional water heater services in West Palm Beach and beyond.

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