How to unclog a dishwasher – expert advice if yours won't drain

It’s common for debris to get stuck in the dishwasher filter, but if your clogged dishwasher is left untreated it can become unhygienic and start to smell, or the water could be redirected to your kitchen sink. 

Like knowing how to unclog a toilet without a plunger, being aware of how to unclog a dishwasher quickly and properly is key to ensuring life at home runs smoothly. 

Fortunately, cleaning a dishwasher regularly, and good stacking practice – primarily not clogging the dishwasher with lots of food debris left on cookware – will mean you won't have to unclog yours too often. However, when you do find you have to tackle this unpleasant task, and possibly unclog your sink as a result of the dishwasher blockage, you need to know how to do the job like a pro.

We asked the experts for their advice on how to spot a dishwasher that is becoming clogged, prevent and reverse it, in just a few simple steps. Plus, we have home remedies for keeping your dishwasher unclogged in future.

How to unclog a dishwasher

First things first: how do you know if you need to unclog a dishwasher? Andrew Bramley, a pure water professional at Pure Freedom, suggests we look out for these signs to see if your dishwasher is clogged:

• Gurgling from inside the dishwasher while the cycle is on;
• Water from the dishwasher is backing up into the sink;
• After a cycle, the dishwasher is draining slowly (a key sign that it is becoming clogged);
• Your dishes and cutlery are still dirty after a full cycle;
• Standing water in the bottom of the machine.

If any of these symptoms is obvious, you will need to take these steps to unclog your dishwasher.

You will need:

1. Prepare your dishwasher and cleaning solution

Our experts suggest that the first step to unclogging a dishwasher is removing its filter, cutlery holder and all the racks. 

Next, create a cleaning solution from a mixture of warm water and one cup of white distilled vinegar. Cleaning with vinegar can be very effective and you probably already have some in your kitchen. Leave this to soak in the dishwasher for 30 minutes.

2. Clear out the debris

Although this may be a bit of an unpleasant step, it may be the most important to unclogging your dishwasher. Put on rubber gloves and use a cup to bail out dirty water, and your hands to scoop out food stuck in your dishwasher, remove the filter and wash it under hot water. You could even use a toothbrush to scrub out debris stuck in the crevices of the filter and the bottom of the dishwasher. 

Make sure to check the dishwasher's spray arms for debris, and, if you live in a hard water area, limescale, too.

Next, simply wipe down the inside of the dishwasher with a clean cloth.

3. Put the dishwasher on a hot cycle with vinegar and baking soda

The experts from Marks Electrical recommend ‘filling up one cup full of white vinegar and leave it standing inside an empty dishwasher (on the cup rack is best), then running it on a hot wash. 

'When this cycle ends, take the cup out and measure out a separate cup of baking soda, sprinkling it over the bottom of the machine. Once this is done, you can run the dishwasher again but on a shorter cycle this time.’ 

This home remedy is so effective because of the acidity of the vinegar, which is perfect for breaking down dirt clogging up the dishwasher. As a bonus, it also helps to prevent and remove odors. Using baking soda is the easy solution for removing persistent food waste residue.

By repeating this short task every few months you can ensure your dishwasher stays smelling good and running efficiently, which will ultimately extend the lifespan of this expensive appliance.

How do you unclog a dishwasher that won't drain?

If your dishwasher won't drain, and you have bailed out the dirty water, checked the filter for debris and removed any visible blockages, run a hot wash with vinegar in a standing cup inside, the next step is to sprinkle equal amounts of vinegar and baking soda (a cup each) into the bottom of the dishwasher. Leave for around 20 minutes then run a second hot wash. This should clear the blockage. If it doesn't, the problem may be more serious, and it's time to call in a professional.

Can you put Drano in a dishwasher to unclog it?

You should not put Drano in a dishwasher to unclog it. Drano is a chemical cleaner designed to unclog a shower drain, unclog a bathtub drain or clear clogs in sinks, and it should never be used to unclog a dishwasher. Nor, for that matter, should it be used to unclog a toilet.

Are chemical dishwasher cleaners better than homemade?

Homemade dishwasher cleaning products are effective and require very few ingredients that you may even have already. However, vinegar and baking soda shouldn't be used too often as this may damage the rubber seals in the dishwasher. Using this mixture once a month is enough.

Shop-bought dishwasher cleaning products come premixed, but, say environmental companies such as Branch, you should ensure what you buy is regulated since cheap, unregulated products may contain some ingredients that are toxic. A reliable, highly-rated buy is Beckmann's Service It Deep Clean Dishwasher Cleaner, which you can buy at Amazon.

Why is there water in the bottom of my dishwasher?

Water at the bottom of a dishwasher is usually a sign of blockages in the dishwasher filter (the small, round, sieve-like basket), in the drain hose, drain pump or air gap. The first thing to do is to bail out the water, check the filter and the bottom of the dishwasher and to remove debris. Once rinsed, run the dishwasher to see if the water clears. At the same time, check the garbage disposal. If this is full, the water in your dishwasher may just be a backup, and you may need to unclog the garbage disposal itself. If neither of these works, you may need a professional to help unblock the drain hose or pump.

How can I stop my dishwasher becoming clogged?

A clogged dishwasher can be a nightmare when it disrupts the everyday working order of your kitchen. The best way to avoid it becoming clogged regularly is to ensure food debris, grease and dirt buildup is kept out of the dishwasher and in the garbage disposal instead.

Just as you would clean a washing machine, your dishwasher will most likely have a cleaning cycle, too, that will hopefully do this job for you. Run it at least once a month to keep your dishwasher from becoming clogged in future.