3 Reasons why your dishwasher won’t drain

It can give you a terrible sinking feeling to notice that your dishwasher won’t drain. Seeing a puddle of standing water instead of sparkling clean plates can be a real nightmare and should be dealt with quickly to avoid bacteria building up and creating a stagnant, smelly mess.

It is important to note that if you conduct any DIY work, you must turn off the dishwasher at the mains or unplug the appliance in order to isolate the electric supply. You will also need to isolate the water supply.

The filters are dirty

If your dishwasher won’t drain, the first thing you should do is check your filter. Filters are an integral part of a dishwasher and need to be maintained to keep the machine running efficiently. Filters trap soggy food particles and prevent excess food and grease from being redeposited within the dishwasher.

However, filters can easily become blocked if they are not regularly cleaned. We recommend cleaning your dishwasher filters at least once a fortnight to avoid dirty plates and ensure your appliance’s longevity. Luckily, cleaning your filters is a simple enough task.

Firstly, you’ll need to locate and remove your filters. These are found at the bottom of the dishwasher, below the lower spray arm. Begin by twisting the cylindrical filter to release the filter from the dishwasher. (Typically, these will have arrows to indicate which direction to twist the filter.)

Once the cylindrical filter has been removed, it is then possible to lift the metal mesh filter plate. Have a quick look in the sump, the lower pit located underneath both filters, to check that no large food deposits have fallen into the sump area and are causing a blockage.

To clean the filters, you’ll need to run them under the tap to wash away any food deposits or built-up grease. For extra tough grime, you may want to use hot soapy water with a sponge or even an old toothbrush. Simply replace the filters within the dishwasher once they are clean and grime-free.

The drain hose or sink is blocked

If cleaning your filters hasn’t resolved the issue, then the next thing that could be preventing your dishwasher from draining is a blocked drain hose. The drain hose is an essential component to any dishwasher as it carries dirty water away from the appliance. It is usually connected to the same drain line as the kitchen sink.

While unlikely, the drain hose could be clogged with built-up grime and food debris or may be kinked. To clean out the drain hose, you’ll need to remove it from the dishwasher and sink drain.

The problem could also lie in your kitchen sink. A blocked sink drain is a simple fix if you have a plunger or drain snake.

The drain pump is damaged

Just like dishwasher filters, a drain pump can easily be blocked by leftover food particles and built-up grease. This will prevent the water from being drained after a washing cycle. Any debris that may have found its way to the pump can usually be found near the impeller (a rotor that increases the pressure and flow of fluid).

Foreign objects, such as broken glass, can also easily slip into the drain pump and prevent the pump from working. You should be able to hear the pump struggling if there is a problem here.

Checking the drain pump requires access to the bottom of the dishwasher. This means you’ll need to disconnect the inlet hose and remove the base plate. You’ll also have to take a resistance reading using a multimeter to ensure the pump is functioning correctly. If you feel uncomfortable performing any of these tasks, or don’t want to risk voiding your appliance’s warranty, call a qualified plumbing technician to fix your dishwasher for you.

Drain Doctor are on hand to provide emergency plumbing services across the UK. We offer 24/7 drainage support, where our skilled technicians use the latest advanced clearing equipment to remove blockages efficiently and provide a long-lasting solution. To find out more about our services, contact our expert drainage technicians at Drain Doctor on 0800 707 172.