Why is My Water Heater Making a Popping/Knocking Noise?

It’s unnerving, to hear a popping noise come from your water heater. Of course, as a homeowner and someone who has to live with that water heater, your mind will immediately jump to the worst—and priciest—conclusions. Fortunately, you don’t have too much to be concerned about if you hear your water heater making a popping or knocking noise. In fact, the solution is something even the amateur DIY handyman can accomplish with just a few tools. But first, let’s talk about why your water heater is making all of these unsettling noises.

Your Water Heater May Have Sediment

Without a plumber onsite to troubleshoot your issue, it’s impossible for us to tell exactly what’s going on with your water heater. However, if you hear your water heater popping—and it sounds like you’re trying to microwave popcorn—then it’s most likely a simple build-up of sediment at the bottom of your unit. Is it a serious issue? No, not really, however, your heating bill may rise as a build-up in sediment does cause your water heater to run less effectively compared to if it was operating normally or without issue.

What is Sediment & Why Does it Become Noisy?

Sediment itself is simply loose minerals, which are often found in the water your unit is heating up. This can become a larger issue or build-up if your water is “hard,” meaning it is packed with denser minerals, which can cause extra sediment to occur. Fortunately, having some sediment in your water heater isn’t an issue for residents, however, it can negatively affect the health of your water heater and create these unpleasant noises.

So where does the popping/knocking noise come from? Sediment that has been given time to accrue at the bottom of your tank will form a layer of minerals that can trap water underneath it. As your water heater begins heating up that trapped water, it will attempt to escape from that layer of sediment and create a popping, or knocking, noise. This effect is made in the same way a pot of boiling water will create noise as bubbling water attempts to escape through the lid of the pot.

Is This a Big Issue & Can I Fix It On My Own?

Allowing sediment to accrue and build up over time won’t immediately cause you issues. However, when a water heater has these layers of sediment in its tank, it can negatively affect the health of the unit in the long run. Since your water heater is forced to operate longer, since it’s struggling to heat the water in its tank properly, it could cause the unit to overheat, which can deteriorate the tank’s protective inner lining—which can ultimately result in leaking. So, while the solution is simple, it’s also necessary.

For homeowners, the next question that likely comes to mind is—is this a big issue and how much will it cost to repair? Fortunately, if sediment is the problem, the “solution” is really just to flush your water heater. While you can call a plumber to do this process, which is recommended if you don’t feel comfortable doing it yourself, let’s walk through what flushing your unit would look like if you wanted to complete the task yourself.

Wearing heavy-duty gloves to protect your hands, turn off your water heater—or set the temperature to “Pilot” if you’re using a gas-based unit—and be sure to turn off your cold water shutoff valve to prevent cold water from entering the tank. Let the unit sit for 30 minutes to let everything cool down. Then, connect a garden hose to the drain valve located at the bottom of the tank and place the other end of the hose somewhere where water and sediment can drain. Open a hot water faucet somewhere in your home to prevent a vacuum from forming and open the water heater’s drain valve. Pull the tab on the pressure relief valve to get the water in the tank moving and let it drain completely. Once it’s been given time to drain, turn on the cold water valve to flush out the remaining sediment and once the water begins to run clear, let the cold water begin refilling your tank. Got that?

Do You Need a Plumber?

If it seems over your head, again, do not hesitate to call a plumbing company to do the job for you like 535 Plumbing. Learning how to flush your water heater is a good skill to have, as doing it annually is recommended to keep sediment from accumulating and growing into these layers.

535 Plumbing – Your Hawaii Water Heater Experts

If you live on Oahu and are in need of a licensed plumber, choose 535 Plumbing for the job! Our team of professional Oahu plumbers are highly skilled and our excellent customer support representatives will work with you to schedule your appointments at a time you most convenient. Learn more and schedule an appointment by calling (808) 300-0535, or Visit Our Contact Us Page. Mahalo!