How To Unblock A Dishwasher

If your dishwasher isn’t draining or washing as well as it should there is likely a blockage somewhere that is causing a problem. Thankfully, unblocking your dishwasher is usually a fairly easy process and can be something you can do yourself. 

Here at VHL, we are experts in unblocking clogs and blockages in a wide range of household appliances, such as a dishwasher, and have created this handy troubleshooting guide to help. Follow these steps on unblocking a dishwasher and our expert advice will have you back to having sparkling wine glasses, pristine plates and spotless pans before you know it. 

Table of Contents

How Do I Know My Dishwasher Is Blocked?

If there is standing water in the bottom of your dishwasher, there is a good chance there is a blockage preventing your dishwasher from draining the water away. In addition, a blockage in your dishwasher’s sprayer arms will leave your dishes dirty after a wash cycle. 

What Causes A Blocked Dishwasher?

A blocked dishwasher is usually caused by either food debris or pieces of plastic, ceramic or glass that have come loose from the items being washed. 

Finding The Source Of The Blockage

Here’s where your dishwasher is most likely to be blocked up:

  • Food debris getting caught in the filter

  • The waste hose become blocked

  • The sink waste pipe is blocked 

  • The dishwasher drain hose is blocked

  • The sprayer is clogged, leaving dishes dirty after a wash cycle 

If it isn’t clear what the cause of the blockage is, start with the dishwasher’s filter. Then, move on to the waste hose and then the sink waste pipe. Finally, check the dishwasher’s drain hose.  

If your dishwasher is draining but leaving your dishes dirty after a wash cycle, the problem will be with your sprayer arm.

Turn Off Your Dishwasher Before Starting Work

Before you begin working on your dishwasher, make sure that it is turned off at the mains and unplugged. 

How To Fix A Blocked Dishwasher Filter

If there is a lot of standing water in the bottom of the dishwasher, the first thing you should check is the filter. A dishwasher’s filter job is to catch any leftover food debris and loose objects before they can cause further problems to your dishwasher. This does mean that filters often get full of food debris from dirty dishes. 

Blocked filters are a common cause of dishwashers not draining so should be the first thing you check when you are having problems with your dishwasher. Thankfully, they are easy to check and fix. Regularly cleaning your filter can also prevent blockages from occurring. 

How To Fix A Blocked Dishwasher Filter

You will find the filter at the bottom of the dishwasher. It comes in three parts and is usually easy to remove and clean. Before attempting to remove the filter, be sure to turn the power to your dishwasher off at the mains.

If the water is still pooling in your dishwasher after you have thoroughly cleaned the filter, then the issue is likely something else, and you should move on to the next steps. 

How To Unblock Your Dishwasher Waste Hose

If cleaning the filters doesn’t fix the problem, there might be a blockage elsewhere. A blockage could be happening further down the dishwasher waste hose. To check the waste hose, you’ll need to go behind the dishwasher. Isolate the water supply to the machine, then ease the dishwasher away from the wall. 

If you have a freestanding machine, you and one other person will be able to pull it away from the wall. However, if you have an integrated model it will be harder to move. It may be easier to call a professional for help if your dishwasher isn’t freestanding.

Check The Sink Waste Pipe For Blockages

In some houses, a dishwasher waste pipe is connected to the kitchen sink’s waste pipe. If water is draining away slower than normal from your sink, or not draining at all, there could be a blockage, which can sometimes be the source of the blockage in your dishwasher. 

How To Unblock Your Dishwasher Drain Hose

Another cause of your blocked dishwasher could be the drain hose. A blocked drain will cause dirty water to collect in the bottom of the machine, along with food debris which can lead to bacteria. 

How To Unblock Your Dishwasher Spray Arms

If your dishwasher is failing to clean your dishes after a wash cycle, there may be a problem with your spray arm. Your dishwasher spray arms are the part of your dishwasher that spin around spraying hot water on your dishes.

Similar to the filter, the spray arms can get clogged with food residue and grime. This means that water doesn’t spray out of the arm as it spins around, so the dishes don’t get cleaned fully. Thankfully, it is fairly easy to clean your dishwasher’s spray arms.

How To Unblock Your Dishwasher Spray Arms

How To Avoid Dishwasher Blockages

There are a few things you can do to help prevent your dishwasher from becoming blocked in the first place. Rinsing your dishes and removing any leftover food debris before putting them in the dishwasher is a great way to prevent the build-up of blockages. Most standard dishwashers can’t cope with the build-up of food debris, which ends in blockages. 

In addition, regularly cleaning your dishwasher’s filter under warm running water and doing a monthly service wash can prevent the build-up of dirt, grease and food particles that lead to blockages.

How To Avoid Dishwasher Blockages

How To Do A Monthly Service Wash On Your Dishwasher

Constant upkeep of your appliances, such as your dishwasher, can prevent problems from turning into a bigger, more expensive breakdown. A monthly service wash of your dishwasher can help prevent the build-up of dirt and grime that can build up and cause blockage. 

To perform a monthly service wash, put your dishwasher on a full cycle while it’s empty with a small amount of white vinegar and baking soda poured in. In addition, regularly checking the areas discussed above will help you prevent blockages from forming, ensuring your appliance continues to run at peak performance for longer.

How Much Water Does A Dishwasher Use?

Many people mistakenly believe that a dishwasher uses more water than washing dishes by hand. In fact, it’s estimated that the average dishwasher actually uses around 75% less water compared to washing dishes by hand. 

The average dishwasher only uses 10 to 12 litres of water per wash cycle, while it is estimated that hand washing dishes use around 49 litres of water. So not only are dishwashers a convenience item, but they are also better for the environment and your water bill.

Consider Getting A Professional In

If you have followed the DIY steps outlined above and you still can’t get your dishwasher to work properly, then you may need professional help. 

Here at VHL Facilities, we provide a 24/7 emergency plumbing service in the Greater London area which includes unblocking clogged drains, high-pressure drain jetting and drain cleaning. VHL are a local plumbing and heating specialist with extensive experience in providing a range of services throughout London. 

No matter what the problem is with your dishwasher, our trained and qualified plumbers and engineers can help. Get in touch with us by phone on 020 3918 6405 or Book Online to arrange for a visit and same-day quote.

Frequently Asked Questions

No. Drain unblockers contain extremely strong chemicals that should only be used in regular drains. If you try to use a drain unblocker in your dishwasher it could leave behind harmful chemical residues that can then contaminate your cutlery and crockery. 

Dishwasher salt is used to prevent a build-up of limescale in your dishwasher, so it won’t really stop blockages as they are usually caused by food and grease.

It’s usually a blockage in the filter, the sprayer arms or the drain hose. You need to locate and clear the blockage by cleaning and unclogging each item.

If you’ve checked and cleared your dishwasher filter, sprayer arms and drain hose and your dishwasher is still not draining, you could have a faulty drain pump. In this case, it’s time to call a professional.