Fixing Bosch Dishwasher Draining Issues
How Do I Unblock My Dishwasher Drain?
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:
- Check the filter
- Clean the air gap
- Check the drain hose
Learn how to do each of these procedures, with video tutorials, below.
1. Check the Filter Inside the Dishwasher First
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.
- Locate your air gap. It's usually a little hood or cylinder at the back of your sink.
- Remove the cover. Most just unscrew or pop off by hand, but some have a small screw that holds it in place.
- 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 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.
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...
- a bucket
- a screwdriver
- 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 drain that's exposed under the sink.
- 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.
- 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.
Questions & Answers
- Helpful 9
- Helpful 6
Why will it not drain when the drain hose is clear?
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.Helpful 3
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?
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.
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?
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
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