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How to Fix Bosch Dishwasher Draining Issues

I found dirty water pooled inside our Bosch dishwasher. Here's how I repaired the problem and a DIY troubleshooting guide for fixing yours.

See that pool of water? Our Bosch dishwasher was not draining.

See that pool of water? Our Bosch dishwasher was not draining.

My Bosch Dishwasher Isn't Draining

After our built-in Bosch ran a cycle, the bottom of the dishwasher was still full of dirty, free-standing water.

Here's how it's supposed to work:

There is a drain pump in the dishwasher that pushes the water out through a hose which typically runs from the dishwasher to either the sink's garbage disposal or the air gap. (Our air gap fits on the top of our sink. From there, another hose connects to the garbage disposal.)

If your dishwasher is not draining, something along this pathway is blocked or broken. Here are the troubleshooting steps to take.

How to Drain a Dishwasher

  1. Check and clean the filter.
  2. Clean the air gap for clogs and damage.
  3. Check the drain hose.

Learn how to perform each of these procedures, with a video tutorial, below.

1. Check the Filter Inside the Dishwasher

There is a screen in the bottom of the dishwasher that is supposed to block large debris from going into the drain hose, but sometimes pieces of food get through and clog the hose. The video below shows you how to check and clean the filter. If you find a big piece of food or glass, remove it and then run the rinse cycle to see if the dishwasher drains. If it still doesn't, move to the next step.

2. Check the Air Gap for Clogs

The most common problem that prevents a Bosch dishwasher from draining is small bits of food caught in the air gap. Luckily, this is very easy to fix.

  1. Locate your air gap. It's usually a little hood or cylinder at the back of your sink.
  2. Remove the cover. Most just unscrew or pop off by hand, but some have a small screw that holds it in place.
  3. The top of the air gap has a small piece that can be removed by depressing the small hooks. Remove the top and clean out anything clogged inside.

How it's supposed to work:

Water is pumped from the dishwasher up through the air gap (that's the built-in plastic tube) and then usually down through a larger hose to the garbage disposal. The problem is that when the water hits the top of the air gap, small bits of food can get stuck between the plastic lid and the built-in tube. This prevents the hose from working efficiently so the dishwasher doesn't completely drain. It's amazing what a huge problem a tiny bit of food can cause.

If you remove a bunch of debris, the problem is likely solved. Run the dishwasher on the rinse cycle and see if all the water is pumped out. If not, proceed to the next step.

What if I don't have an air gap?

Some units skip the air gap and drain directly into the garbage disposal by using what is called a high drain loop, which is an extra-long (at least 32" high) drain pipe that's fastened to the underside of the countertop. If you have a high drain loop, skip to step #3.

Pull the cover off your air gap and check for debris and tiny bits of food.

Pull the cover off your air gap and check for debris and tiny bits of food.

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Read More From Dengarden

How to Unclog the Air Gap

3. Check for Clogs in the Drain Hose

To detach a drain hose from the air gap (or garbage disposal), you'll need:

  • Bucket
  • Screwdriver
  • Pair of pliers

Instructions

  1. Using a screwdriver and the pliers, disconnect the drain hose that is attached to the air gap (or garbage disposal), drain the water, and check if the hose is blocked. You'll only be able to see the section of the drain that's exposed under the sink.
  2. To see if the drain hose is blocked, run the dishwasher on the rinse cycle and hold the hose over the bucket. If the dishwasher doesn't drain, then the drain hose is blocked. You might try to use a plumbing snake or a hanger to push out the clog.
  3. If you can't find the clog in the section of drain under the sink, it's likely in the portion you can't see, directly behind the dishwasher. Most drain hoses run through a hole in the cabinet and the dishwasher may need to be pulled fully out for closer inspection. Before you pull it out, you'll need to unscrew the two L brackets that connect the top of the dishwasher to the underside of the counter. You may also need to adjust the height of the dishwasher by screwing its feet down lower to give you clearance at the top. If this is too difficult, it might be time to call a plumber.
This is an air gap that has been disconnected from the drain hose and the garbage disposal.

This is an air gap that has been disconnected from the drain hose and the garbage disposal.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Questions & Answers

Question: What does a Bosch e23 code mean?

Answer: An e23 error on a Bosch dishwasher is an electrical problem with the drain pump. It may require replacing the drain pump.

Question: Why would clean water gather at the bottom of a dishwasher if it's not run every day?

Answer: It’s possible that the drain hose bypasses an air gap and connects directly to the garbage disposal. Without an air gap water from the sink can flow back to the dishwasher so that you might have sink water flowing back in.

Question: What is the check valve on drain hose and what does it do?

Answer: A check valve is sometimes used in place of an air gap. Its purpose is to prevent water from flowing back in the opposite direction.

Question: Why will it not drain when the drain hose is clear?

Answer: There are a number of possibilities. The most common is a clogged airgap, clogged filter, and a bad pump. The first two are easy to remedy. A bad pump is more expensive. There is also the possibility the control board is bad. Look for error codes and call an appliance repair shop and they may be able to assist you.

Question: I have a Bosch dishwasher that I've had for about 5 years. Tonight, it just stopped draining, and the washer started beeping. I checked the filter, which doesn't seem to be clogged. I check drain line and it didn't have much water in it. The washer will not rinse, or wash anything. Any suggestions?

Answer: Sometimes the beeping will be accompanied by an error code. Check for an error code. It sounds like you have done the basic troubleshooting. I'd try calling the appliance shop where you purchased it and see if you can talk to a repair person. They will often have additional troubleshooting tips or be able to give you an estimate of what the likely part will cost to replace it.

Question: My 2017 Bosch dishwasher isn't draining properly. It shows E24 as the error code. I took out the filter and cleaned it, but there is a backlog of dirty water. Can you suggest what I might need to do?

Answer: The e24 error code may be associated with a few problems. For the DIY person, we suggest first making sure the check valve is clear. Next, check the hoses for kinks, and make sure the filters are clean. These are the basic steps. After this, the dishwasher may have an issue with the pump or control panel and will require pulling the dishwasher out. For most folks, this is where we recommend calling a repairman. For newer models, it's possible that it is still under warranty.

Question: Why would water be coming out of the air gap of my Bosch dishwasher?

Answer: There are a few possibilities. Air gaps are intended to prevent water from running back through the hose. So, two primary possibilities are there is a blockage or kink in the hose or a clog in the air gap. Another, but rather unlikely cause is the air gap is below the water causing a siphon of sorts. Take the air gap apart and check for small chunks like a piece of carrot. This is likely the culprit.

Question: My Bosch dishwasher keeps coming up with either "E18" or "E14" on the display. It did not empty and had a large pool of water in the bottom. Any suggestions?

Answer: These errors aren't associated with a draining issue, but rather a flow issue and a water level issue. Likely something is preventing enough water from flowing into the dishwasher.

Question: The water in my dishwasher sits below the filter, in the sump. Would vinegar and bi-carb remove any clogs or do I have pull out the machine and check the pipes manually?

Answer: A little water sitting below the filter is normal. It’s possible that there isn’t a check valve which can cause it or the way the older Bosch dishwashers work, they don’t completely dry, so a small amount of water can gather. That said, a rinse cycle with vinegar won’t hurt anything. The only downside is this small amount of water below the filter can start to smell if the dishwasher is used infrequently. If that’s the case, leave the dishwasher cracked open to dry and clean the filter. For a very small amount of water, below the filter, I wouldn’t pull the machine to check for clogs.

© 2010 Paul Edmondson

Comments

Karl Cole on January 03, 2020:

Got 3 times an error message on my Bosch 2017 model Ascenta dishwasher. I found the cause of the problem.. *Simply remove the kitchen sink drain plug to let evacuate the pressure from the pump! Otherwise a sensor will send an error message (E19 E35 and others) ''thinking'' that something is stocked at the pump.. which is not the case!!!

Matty on August 02, 2019:

I have a 5 year old silenceplus shxm66 model. Mice ended up chewing on the 300v wires to the heat pump coming from the main control. I was getting a E01 code and so decided to splice/repair the damaged wires. Now it’s just an E23 code. Is there a service diagram for testing resistance of the heat pump or control panel? Which component would have been most likely to be damaged if a mice had shorted the unit while it was operating? Thanks!

Colin Livingstone on May 13, 2019:

I have a SMS40T32UK dish washer. There is no easy way to access the water pump beyond the impeller.I think grit and fat deposits have bypassed the impeller and filters, yet this appears to be a sealed unit.Any ideas or fixes?

Sharon calkins on September 05, 2018:

Our Bosch silenceplus 50 dBA will not stop running even if we open the door. It just keeps running

dutch on August 26, 2018:

my dishwasher came up with code E24 ,,,CLEANED MY PUMP FILTER, CLEAN MY AIR GAP, still had stuff that I could not get to,,,,So I put a cup over the opened air gap and turned the rinse cycle and FLUSHED the line, washer now drains

CharlesDickens24 on August 21, 2018:

I had the draining problem. After trying a few things, I realized I replaced my garbage disposal but forgot to knock out the plug the drain hose for the dishwasher connects to. Problem solved.

JMills1 on April 11, 2018:

I have a Bosch Ascenta dishwasher that has worked well for about 3 years. Just after it was installed, the unit would drain completely and then fill with water from the drain about 1-1.5 hours later. The issue was repaired and there were no further problems. Now the issue has resurfaced again. The repair person cleaned the filter and hose and replaced the pump. This has not solved the problems. Any ideas? thank you in advance. It looks like this is the same issue JS is having.

Paul Edmondson (author) from Burlingame, CA on January 05, 2018:

Clean the filter, and check for any clogs. It's possible the motherboard or another part has an issue, that will need to be replaced.

JS on January 04, 2018:

My problem is the dishwasher completes its cycle, I turn it off and empty the dishwasher. This doesn't happen all the time. But, at some point, you could hear a short hum and what sounds like water coming through, and sure enough there's water at the bottom of the dishwasher. I have to run a short cycle to empty it. Any thoughts?

tom on October 01, 2017:

Alan,

I don't have an air gap either. There is a large plastic hose from the dishwasher to the disposal. The water pools in the drain below the filter and can smell quite bad if the washer is not used. HOw can I get the water to drain out. Thanks, Tom

Paul Edmondson (author) from Burlingame, CA on September 14, 2017:

@Alan if it's not completing the cycle, that's likely a different issue where the water in the bottom is a symptom.

Alan on September 13, 2017:

Paul, thanks for the info. It sounds like you're saying to Paul that it's normal for there to be a little pool of water in the very bottom sump between cycles? There are 1 or 2 cups in mine. I can't decide if that's normal or not.

Our Bosch gets stuck at various points in the mid rinse cycle and I'm trying to determine if it's a pump issue or not.

Paul Edmondson (author) from Burlingame, CA on September 10, 2017:

@Glenis, A little moisture is fine and if you clean the filter that should prevent it from smelling. You can also leave the door slightly cracked open and that will help as well. I don't think it impacts the dishwasher, but the newest models do have a different drying feature. I think it's more of a perception issue.

Glenis Rix on September 09, 2017:

A Bosch dishwasher is a fairly new addition to my kitchen and I had the same concerns as Jerry, so your response to him has set my mind at ease to some extent. But I'm concerned that if I'm away from home for an extended time (e.g. vacation) and therefore not using the machine regularly the stagnant water might breed bacteria and start to smell unpleasant. I'm wondering if incomplete drainage a design fault?