Most people have come to terms with the fact that dishwashers are noisy during the wash cycle. You’ll hear the sound of water spraying the plates, the grinding of the motor, the snap as you open the door — it’s all fairly standard. But what should you do if your dishwasher starts making noise when it’s off?
Before we get to answering that question, let’s discuss the range of sounds a dishwasher can make. Since most of them only occur during a wash cycle, the ones we’ll be talking about today should be outliers. Knowing how to identify normal sounds may help you eliminate them when you’re trying to figure out what’s wrong with your appliance.
Regular Dishwasher Sounds
Most dishwashers have a standard range of noises they’re capable of producing. The door clicks as you close it, the controls beep as you select the program you want. Soon after, you hear the spray of water hitting your dishes and the constant drone of the drain pump.
The compartment on the inside of the door snaps open to release the dish detergent. After the final rinse, the fans in the door spin to let the steam out, humming and grinding as they do. These are all fairly normal sounds to hear from a kitchen appliance.
As you’ll see, there are only a few things that could cause a dishwasher to sound off outside of a wash cycle. However, there are plenty of suspicious noises you’ll want to pay attention to while the machine is working.
If you loaded plates that are too large or positioned the items improperly, you could hear rhythmic banging, knocking, or rattling. Alternatively, if the rotating spray arms chip off a piece of a mug, it might end up grinding against the blades in the drain impeller.
Worst of all, these unpredictable sounds can happen even if you have the quietest dishwashers on the market. After all, they’re usually the result of improper handling of the appliance. But could we say the same for the kind of sounds you might hear when the dishwasher is off?
What Makes a Dishwasher Make Noise When It’s Off?
As far as I can tell, three things could produce noise even when your dishwasher is off:
- A “water hammer” could present as a banging sound anywhere in your plumbing system, including the pipes around your dishwasher
- Having a loose water inlet valve could result in a low hissing sound
- Your dishwasher could be continually draining itself — which itself may be the result of a loose valve!
But which of these theories could explain the kind of noise you’re hearing? More importantly, how can you fix the issue once and for all?
First things first, let’s talk about the least likely answer — hydraulic shock. If you’ve ever heard a stray clanging sound in your water pipes, it was probably the result of a water hammer. This phenomenon occurs when we suddenly shut off a water inlet valve, making the water slam back into the pipes.
Because of the way our plumbing systems are designed, it’s possible to shut off a valve in one place and have the sound occur in another. So if someone shuts off the tap after washing their hands in the bathroom, you might hear the bang in the pipes around your dishwasher.
As I’ve explained in the article I’ve linked to, you could prevent this kind of noise by installing a simple water hammer arrestor. But since this isn’t the most likely cause of the sound you’ve been hearing, we’re going to move on to the other explanations.
Worn Water Inlet Valve
All dishwashers need access to water, which is provided by a water supply pipe. The pipe is connected to a water inlet valve which is usually located under the appliance. But like any other plug, that regulator can loosen over time, causing pressurized water to slip into the dishwasher accompanied by a steady hissing tone.
When the valve loosens, the water will either leak on the ground or into the appliance. Luckily, the solution to this particular problem is fairly simple. You can tighten the valve to stop it from leaking or replace it with a new one. Before you do anything, though, make sure to cut off the power and water supply to the appliance. You don’t want to have to deal with a flood or an electrical mishap.
Many dishwashers have an anti-flood feature that can detect and eliminate excess water in the machine. The feature should work independently from the wash program so it could fire up the drain pump motor even when the appliance is off.
Several things could make the drain pump work overtime, including a leaky water inlet valve. However, if that’s not the issue, you should check the other valves and make sure the drain line has been correctly routed to the nearest floor drain.
Now, even if you do these things, the anti-flood device will remain active until you manually reset it. To do that, you’ll need to get under the dishwasher. After removing the access panel below the machine, you should immediately see a water reservoir filled with dirty water with a polystyrene float in the middle. That’s actually the switch — as long as it’s floating, the device won’t reset.
Use sponges and rags to get as much of the water as you can out of the tray. The polystyrene should touch down on the plastic base on its own, but feel free to press it down. Since it’s deep under the dishwasher, you could use a long utensil to gently press the part down. That should reset the anti-flood device and stop the drain pump from working when it doesn’t need to.
How to Soundproof Your Dishwasher
If you decide to call in the professionals instead of fixing the dishwasher yourself, you could focus on reducing the noise. Even if you’re waiting for another model to arrive, you could still use the one you have. There are several things you can do to muffle the sound, including:
- Soundproofing the dishwasher with blanket insulation
- Covering the front of the machine with a moving blanket
- Soundproofing the kitchen, particularly the door
But ultimately, figuring out why your dishwasher is making noise when it’s off shouldn’t be all that difficult. As always, the most important thing is knowing where to start looking for the answers!