Why Won’t My Dishwasher Drain? Answers & Solutions

A Dirty Plate With A Sad Expression

A dishwasher that won’t drain can be a real headache for homeowners. It can be tempting when you see a puddle of standing water at the bottom of your dishwasher to despair. But the cause behind a dishwasher that won’t drain is often easy to fix at home, returning your dishwasher to full working order with ease. 
In this guide from Coastal Drains, we’ll look at some rules for dishwasher use that can help prevent further blockages and a series of troubleshooting steps to remedy a non-draining dishwasher quickly and easily. One important thing to note; you must turn off your dishwasher at the mains before you commence any work on it. If you find this guide useful, you may enjoy our other guides on how to fix a slow draining toilet and how to unclog a drain.

How to Prevent Dishwasher Blockages

Putting Tab Into Dishwasher

Keeping your dishwasher in good condition can help avoid blockages. When inserting bowls, plates, and cutlery into your dishwasher you should make sure that all solid food waste has been scraped into the bin. This can help to avoid pieces of food being stuck within the filter or drains of your dishwasher.

Another important maintenance method is to run a monthly clean of your dishwasher using dishwashing cleaning tablets or liquid. These tablets or liquids, run through on an empty cleaning cycle, help to remove grease, limescale, and foul odours from your dishwasher. This should be done at least once a month. Keeping your dishwasher clean, including the seals and the spray arm, can help maintain good working order.

How to Fix a Dishwasher That Won’t Drain

Technician Checking On Modern dishwasher filter

If you are wondering why your dishwasher won’t drain, there are a variety of places where the problems could have originated within your machine. Here are some quick and easy home methods to locate and solve the reasons your dishwasher won’t drain. Remember to turn off your dishwasher at the mains before you start work.

  1. Check For Blockages

Food and materials blockages could explain why the water isn’t draining properly in your dishwasher. Water drains from your dishwasher through a hole at the bottom, so when plates with excess food are placed within a dishwasher, this can cause blockages as it is being flushed away. Small items you are cleaning can also prevent your dishwasher from draining, so should either be placed within a cutlery basket or cleaned by hand. Check the bottom of your dishwasher to make sure there isn’t a piece of food or a small item blocking the water flow.

  1. Check the Filter

If the water isn’t draining in your dishwasher, the issue could lie with its filter. A dishwasher filter serves a vital role in preventing small pieces of food from blocking your drain or getting onto your newly clean plates. You need to clean the filter and empty it regularly. They are located on the bottom of the dishwasher, with a removable cylinder. Take out the filter by turning and pulling it out. Empty any solids from the filter, then use a soft cloth or brush to carefully scrub the wireframe clean with soapy water.

Once you have cleaned the removable filter, check the sump. The sump is the hole below the filter, leading to the drain hose. There could be solid food or other debris within the sump, which you must remove. Some models of dishwashers come with a separate coarse filter, a flat plate below the cylindrical filter. Check the owner’s manual to see whether you have a coarse filter. If this is the case with yours, remove and carefully clean the coarse filter alongside the regular dishwasher filter. This can help unclog your dishwasher, and regularly cleaning the filters can help prevent future drainage issues.

  1. Check the Drain Valve

The drain valve is located underneath the dishwasher, helping to remove condensation from within it. A faulty drain valve can be the cause of a dishwasher that won’t drain, as the gate arm allows water to drain out of the dishwasher. To check your drain valve, open the kick panel at the front of your dishwasher. It should be by the motor, consisting of a gate arm and springs. Make sure that the gate arm can freely move and that the springs are attached. If the drain valve is broken it will need to be replaced, which may require getting in a professional. A professional will also be able to detect if there are any issues with your drain pump, located on the bottom of your dishwasher, or your air gap, located within certain dishwasher models.

  1. Use Vinegar and Baking Soda

If the water won’t drain in your dishwasher, a mixture of vinegar and baking soda can be used as a simple at-home method to unclog it. Make a 50/50 mix of vinegar and baking soda of about 400ml, and pour this mixture into the bottom of your dishwasher. Leave it for about half an hour, and then check if the mixture has been draining. If it is starting to drain, pour hot water into the dishwasher to help run the mixture through. Then run a rinse cycle in your dishwasher. This method can help to loosen clogs and blockages within your machine, helping your dishwasher to properly drain again. 

  1. Blockages Within Your Drainage Network

A slow draining or non-draining dishwasher can also be caused by issues within your drainage network. The wastewater pipe from a dishwasher is connected to your kitchen sink’s wastewater pipe. This means that blockages within your drains can cause water to not drain from your dishwasher. Firstly, check the drain hose from your dishwasher is unobstructed. If your wastewater pipe is flexible, it can become stuck or kinked, obstructing the water flow.
If the pipe from your dishwasher is fine, it is worth checking the drain in your sink. A blocked sink can be spotted in several ways including if water is slow to drain from it. If you notice gurgling sounds from your sink, or smell unpleasant odours from within it, this could also be a sign of a blocked drain. We have an article about the causes of blocked drains offering some home solutions. If the cause of the blockage is more severe, it may be time to call in an expert.


Expert Drain Unblocking From Coastal Drains

At Coastal Drains, we offer excellent drain unblocking services across the South East. We conduct CCTV drain surveys, where we utilise state of the art equipment to locate and document issues within your drainage network. CCTV drain surveys offer effective troubleshooting for any drainage issue. We can unblock any drain, utilising drain rodding or high-pressure drain jetting. If the cause of your dishwasher not draining is to do with blockages in your pipes, our skilled and friendly team will be available to unblock them for you. 

We offer a low price guarantee on all of our work, with 24/7 emergency call outs. Whatever drainage work you need in the South East, Coastal Drain is the clear choice, offering a thorough, professional, and prompt service. If your dishwasher isn’t draining, and you suspect the problem is a blocked drain, give us a call today.

Author: Greg Child

Greg is an expert in drainage and has been in the business for over 30 years. He's the owner of Coastal Drains Ltd and a very, very friendly chap.

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