Why Is My Water Heater Making Noise?
If your water heater is making a strange noise, it’s worth looking into. Noise from a water heater usually means sediment buildup, which indicates that it’s time to get it looked at, or it may mean you need an entirely new water heater.
Popping Like Popcorn
Before you ask, it’s safe to say there is no popcorn being microwaved inside your water heater. (At least from our experience)
When you can hear a popping sound coming out of your water heater, it means that there is a crust of sediment that has built up over time inside your water heater. Water will get trapped under this crust, slowly heat up, and then “pop” out from the crust once it boils. Water expands when heated. If it doesn’t have a place to go, pressure will build up until it escapes all at once. That popping you hear is countless tiny pockets of water constantly heating up and releasing pressure.
Below you can learn more about sediment buildup, its impact, and what to do about it.
Rattling, Rumbling, or Knocking
If your water heater sounds like a big maraca, you might have some sediment build-up floating around inside your tank.
Unlike the popping from a crust inside your tank, rattling sounds could be chunks of sediment floating around inside the storage tank. These pieces of sediment noisily knock on the walls and parts inside the tank when they’re moved around by the turbulent water inside.
Below you can learn more about sediment buildup, its impact, and what to do about it.
What Is Sediment Buildup?
The water we drink and use in our homes has little tiny bits of dissolved minerals (mostly calcium and magnesium) inside it called sediment. For us, this is completely safe. For our water heaters, sediment can eventually lead to a problem.
As your water heater sees use, sediment accumulates inside the tank (if you have a storage tank water heater). You can see something similar happen if you ever leave a pot of water on a hot stove. Eventually, if you forget about it, all the water will be gone, and you’re left with a hard-to-remove mineral deposit on the bottom of your pot. The same thing happens with your water heater but magnified.
Over the years, your water’s sediment slowly accumulates inside the tank and on the components of your water heater. The sediment can form a crust or just sit at the bottom of your tank, but as time goes on, it will harden and begin to cause issues. This is why regular flushing is critical for your water heater’s health before the sediment becomes a problem.
The rate at which the sediment accumulates in your tank is largely dependent on the hardness of your water. Essentially, harder water means that you have more sediment and more sediment means faster build-up inside your tank. If you want to learn more about how your water hardness impacts you and your water heater, you can read about it in our blog, “Do I Need A Water Softener?”
The Impact Of Sediment Build Up
If you’re concerned about what might be floating around in your tank and the safety of your water, you don’t have to be. While it’s not necessarily ideal for sediment to be bouncing around inside the tank of your water heater, all the sediment that’s in there came from the water itself. It’s a safe assumption that anything that accumulates in your water heater comes from the water that you’ve already been using in your home. So you don’t have to worry about an old water heater posing a threat to your health.
The sediment can impact your tank by making it less efficient, or in some cases, it can severely impair function. This is why it’s a good idea to flush your tank annually to remove the sediment build-up.
If your tank hasn’t been flushed in the first 5 years of its use, we don’t recommend you flush your tank.
You can read more about why that is and what your next steps are below.
What To Do About Your Water Heater’s Sediment Buildup
If you’re confident that you have sediment buildup, here are your next steps.
First, you need to find out the maintenance history of your water heater. We have a guide on figuring out how old your water heater is in the section called “So How Old Is My Water Heater?”.
If your water heater hasn’t been flushed within the first 5 years of its use, then we actually recommend that you don’t flush it out. Trying to flush a neglected water heater can cause more problems than it solves. Sediment hardens over time. When we open the drain valve to flush it out, sediment can actually get stuck in the valve and prevent it from closing. What’s worse is that sometimes after you flush a neglected water heater, it can damage your water lines. This is because when filling the tank back up some of the loose, hardened sediment can get knocked loose from the walls of the storage tank. These loose pieces of sediment can find their way into your water lines and cause clogs within mixing valves in your showers, cartridges of your faucets, or the water lines themselves. These examples, just to name a few, can cause damage to your fixtures or cause an overall decrease in water pressure.
The fix to these problems is intensive. It involves pressurizing the water lines then checking the aerators for sediment. It’s best to avoid the issue altogether. That’s why if your tank hasn’t been flushed in the first 5 years of its use, we don’t recommend you flush your tank.
Now, if your water heater is less than five years old or you know that it’s been regularly flushed since it began use, then you can probably flush it yourself. Fortunately, we have a guide that anyone can follow: “How to flush your water heater”, where we show you how to do just that.
Whether or not you know your water heater’s maintenance history it may be a good idea to call your local water heater expert to come check it out for you. It’s best to get an expert opinion before you flush your heater and cause problems for your house’s water lines. They will be able to either fix your water heater or get you set up with a new water heater. That’s especially if the noise persists after you flush out your water heater.
An expert will also be able to tell you if you need to replace your anode rod. The anode rod plays a vital role in making sure your tank doesn’t corrode. The anode rod may be shifting around inside your water heater and cause noise, especially if there is something wrong with it.
Hissing From A Leak
A hiss coming from your water heater may indicate a leak.
One of the biggest issues we run into with water heater leaks is that our customer might say, “Oh, it’s not a big leak, so I’m not in a rush to replace it.”
This is a dangerous mindset!
A small leak on your water heater can rapidly get worse. Imagine this: You take a water balloon, and fill it with water then poke a tiny needle size hole into it. You'll have a small amount of water come out, but it will be slow and not really an issue, right? Wrong. Now you take that balloon and hook it back up to the running faucet. That small hole expands really quickly, then causes the balloon to burst.
This is what will happen every time you use running water in your home. Your water heater receives new water from the city at a high psi. This is all pushing against that small leak which leads to a quick and dramatic failure. Call a professional and get your water heater replaced before this happens.
The first thing you’ll want to do is follow the sound of the hiss to try and locate the source. You’ll want to check all around the heater to see if you can see any water pooling up and see if you can find the leak from there.
When your water heater tank itself has a leak, that means that it needs to be replaced. Unfortunately, unlike some issues with water heaters, when there’s a leak coming from the tank repairing it isn’t a viable option.
If you can determine that the leak is not coming from the actual tank of your water heater you’ll want to get it repaired, but you may be in luck.
If you hear hissing from your water heater, it’s best to call an expert. They’ll be able to help you diagnose the problem and hopefully fix it, or if nothing else, get you a new water heater.
Sizzling, Screeching, And Whistling
Oftentimes if you hear sizzling, screeching or whistling sounds from your water heater that means that water is being pushed through an irregularly small opening through the water heater. This can be caused by sediment or a malfunctioning valve, or another path where water travels through the water heater.
If there is something wrong with a valve on the water heater, it’s worth getting looked at. It may mean that the connection on the valve is faulty or loose, but it could also mean that there is a blockage somewhere in your water heater. The blockage is likely caused, once again, by sediment buildup. The sediment may have accumulated in a valve or pipe where it restricts the opening where water is supposed to flow. This causes water to push through the tight opening and creates the sound you’re hearing.
In this scenario, it’s probably best to call an expert to identify the problem and go from there.
Hopefully, we’ve helped you find the next steps towards a more peaceful, quiet, and functional water heater.