Five Things to Check For a Dishwasher Not Draining

If you’re sitting at home wondering, “Why is my dishwasher not draining?” The professional technicians at Flow Pros Plumbing can help you determine that. 

Below are some questions to ask yourself.

Do you see water bubbling?

Have you seen food particles and plastic at the bottom of your dishwasher?

If you have, you most likely need to call a plumber out to check the drain lines. Before you schedule everything, let’s go through a few things you can check on your own.

One: Check for Left Behind Particles

People love to skip late-night clean-ups sometimes. We get tired and leave too much food on the plates when placing them in the dishwasher. When this happens, here are some things you can do.

If you remove the lower rack of the dishwasher, you can check the drain to see if anything is blocking it. A piece of paper, plastic, or food can clog up the drain. When you remove the block, the drain should clear right up.

Set up your dishwasher to run on a hot water cycle. If it doesn’t clear up, get a dishwasher-safe bowl, fill it up with 1 cup of white vinegar, and put it in the bottom of the empty dishwasher. The vinegar will break up any remaining pieces of grease, soap, food, residue, and other leftover grime. Then run the dishwasher on an empty hot cycle to get it all clean for your next load of dishes.

Two: Check the Garbage Disposal

Surprisingly enough, the garbage disposal and the dishwasher are connected. Often, a piece of food or garbage is still at the disposal, or the connecting tubes do not allow proper function.

If you think that may be causing the dishwasher’s backup, try clearing the garbage disposal first.

Leave the water on and let your garbage disposal run an additional 15 seconds after the food is done in the disposal. This clears all the remaining food that might otherwise remain in the P-trap drain beneath the disposal. In that case, it can prevent even the top-rated dishwashers from draining correctly. 

Three: Inspect the Drain Hose

The first step you can take in troubleshooting a dishwasher that’s not draining is to pinpoint the type of drain connection that lies under the sink. Under the counter and in the cabinet, look at the installed dishwasher drain hose configuration and see how it seems connected to the sink drain. The following drain connections are what we typically see.

• High loop to disposal: In this part, the dishwasher drain hose enters the cabinet from the dishwasher and loops to the top of the cabinet, where it’s held up and then connected to the garbage disposal.
• Air gap to disposal: In this setup, the hose goes to the top of the cabinet in just the high loop, but instead of having something to hold it in place, the hose connects to a fitting in the back of the sink. Suppose the dishwasher drain connection has an air gap. In that case, a small cylindrical knob will be installed on the sink’s top to allow air to enter and prevent dirty sink water from draining back to the dishwasher. An air gap is like a dishwasher overflow that prevents air locks in the hose.
• High loop to drain: If you don’t have a connected garbage disposal, the dishwasher drain hose should still have a high loop, then connect to the drainpipe. The connection must be before the P-trap on the drain line. Sewer gases can enter the dishwasher and leave a bad smell if it isn’t.
• Air gap to drain: This is the same as the air gap to disposal, just without the disposal. The hose will run to the air gap and then connect to the drainpipe before the P-trap.

Four: Check Your Dishwasher Filters

If something is blocking the filter, it will drain very slowly. Sometimes, a piece of broken glass, plastic, or other particles will get caught there and prevent drainage entirely. It can be plain nasty, honestly. If you think this may be the reason for poor drainage, you can do a couple of things. 

Let’s assume you have a new dishwasher with a manual-clean filter; you first need to know how to access it:

• First, find a screwdriver; at the bottom of the dishwasher, a filter will be covered by a screen. To be sure the screen is clean, you may need to remove it with the screwdriver and clean it out thoroughly. 
• You can find your dishwasher filter on the bottom floor, which can easily be removed by taking out the bottom dish rack. 
• The filter can be found in the back corner of the dishwasher or just under the base of the sprayer arm. You may also have to remove this as well to get to it. People often take this as an opportunity to clean the sprayer arm.

How to Remove Your Dishwasher Filter for Cleaning.

Modern dishwasher filters have two parts: an upper filter and a lower one. The upper filter is usually shaped like a cylinder, and the lower filter generally is a flat piece that sits beneath the upper filter.

Remember, some dishwashers will only have a top filter, so don’t be shocked if you don’t see a lower filter. If you have two filters, you should remove and clean both.

1. Remove your upper filter by gently turning it a notch to unlock it. It should come loose, allowing you to remove it.

2. Remove the lower filter if your dishwasher has one. Lower filters aren’t typically locked, so you should be able to pull it straight out.

Now That You Have Removed the Filter(s), It’s Time to Clean It.

1. Start by taking both filters over to your kitchen sink. Use a soft cleaning brush and mild dish soap to scrub away the debris gently. No scrub brushes? No worries! An old toothbrush or a sponge will also work just as well.

2. Once you’ve scrubbed a bit and your filter looks pretty good, test if it’s clean by running the water through the filter. If it’s clean and clear water running through, you cleaned your filter!

3. Now that you’re done cleaning, put the lower filter back in place first. When you do, ensure the lower filter is adequately aligned with its hole leading to the drainage hose.

4. Once you’ve put the lower filter back, replace the top filter and turn it a notch to lock it back in its place. Turning the top filter until it clicks into place and no longer wiggles or turns at all is essential. Double-check that everything feels in place and locked in before returning the lower dish rack to the dishwasher. Starting your dishwasher with a loose filter could damage it significantly.

Five: Make Sure You Use the Right Detergent

Dishwashers are designed with automatic dishwasher detergents that clean without producing suds. On a stressful day, it’s easy to mistake regular dish soap and put it into the washer, which can quickly create enough suds to keep it from draining properly.

The same problem can occur if you run out of dishwasher detergent or pods and substitute laundry detergent in a pinch. Simply bail out the tub as described above and rerun the cycle using the correct dishwasher detergent.

Still wondering, “Why is my dishwasher not draining?”

There could always be a situation with drain lines that only a trained plumber can identify. If you have tried what we have listed above, you should call an appliance repair service or contact your local plumber at Flow Pros.

Plumbing is not always a DIY fix, and there is good reason to call an expert. You sure don’t want to make the problem any worse. So, contact the friendly professionals at Flow Pros if you have any plumbing issues. They will assess the situation and get your drains unclogged at once.

Contact Flow Pros for all your plumbing needs today.