Question about Tappan 18 in. MDR251RE Built-in Dishwasher

2 Answers

Dishwasher drains into sink

Hello I have an older dishwasher that drains into a spout in the sink but then the overflow runs into our garbage disposal. Just recently it started to drain into the sink. The sink overflow is supposed to drain into the sink but, leaks all over the counters and floors. Is there a simple solution? Before I start removing hoses that may be cloged with food I thought I would ask. Your assistance is appreciated. Thanks in advance. Eric

Posted by on

2 Answers

  • Level 1:

    An expert who has achieved level 1.


    An expert whose answer got voted for 2 times.

  • Contributor
  • 1 Answer
Re: Dishwasher drains into sink

As background, the dirty water typically goes from the dishwasher to a small tube within a tube, and that goes to the disposal. This ensures that your dishwasher does not back up in the event of a clog.

The problem is likely that the tube that links the thing you see next to your faucet to the disposal is either totally or, more likely, partially blocked.

I recommend taking the entire flex pipe off and inspecting. In my case it was about 80% blocked, so a simple test whereby water was pored down failed to show the issue.

Once I took it apart and gave the tube a plumbing version of an angioplasty all was well.

Posted on Feb 25, 2009

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.


    An expert whose answer got voted for 500 times.

  • Master
  • 1,314 Answers
Re: Dishwasher drains into sink

Im going to try to help but cant quite understand what your talking about is this a portable or built in washer just reply it will e mail me

Posted on Jan 01, 2008

Add Your Answer

0 characters

Uploading: 0%


Complete. Click "Add" to insert your video. Add


3 Points

Related Questions:

1 Answer

Our sink and garbage disposal was clogged up. We got the sink unclogged, but the dishwasher had dirty water in the bottom and won't drain.

Your dishwasher drains into the garbage disposal. It you tried to use a plunger to clear your clogged sink or run the disposal with to much junk in it you may have force debris into the dishwasher drain hose. With both the dishwasher and garbage disposal disconnect from power disconnect the dishwasher drain hose from the garbage disposal. This is usually about a one inch black hose. Clear out any debris in the hose and inlet nipple on the garbage disposal. If debris is compacted far down the hose it will need to be disconnected from the dishwasher end and remove to clear the blockage.

Good luck!

Feb 10, 2012 | Asko 1385 Dishwasher

1 Answer

Dishawasher floods

Two possible reasons come to my mind. First, and simplest, I've seen Dishwasher installations that did not use a air gap in the Dishwasher drain (usually a dome device mounted on the back of the kitchen sink or sometimes mounted in the wall just above the sink in older homes).When an air gap is not used, it is imperative that a high loop is formed in the dishwasher drain line, and tied up in that position (usually under the kitchen sink,as high as possible- the underside of the sink faucet usually works, or a screw into the bracing under the counter top to wrap a soft wire looped around the drain hose to hold it there permanently). If you do not use a air gap, or have a high loop in the dishwasher drain hose, then likely you are getting a back flow of dirty water into your dishwasher from the drain plumbing to which the dishwasher is connected (likely the garbage disposer or the tail from the sink basin.) So every time you either run the disposer (if you have one), or drain the sink basin, some of that contaminated, dirty water may be siphoning back into the dishwasher There are some exceptions, as some dishwashers including some whirlpool models, have a anti siphon ball device built into the drain pump housing.( You should also check your local plumbing code. They may require an air gap in your dishwasher drain line regardless of anything else.) Secondly,the water inlet valve may be sticking open, or not completely seating closed after the fill cycle. This could be indicated by a very gradual accumulation of clean, clear water in the bottom of the tub, to the point of completely filling the bottom of the tub to the point of overflow at the dam at the front bottom of the tub. The speed of overflow will be determined by how poorly the diaphragm inside the valve is seating. If you suspect this may be the problem, pull the rubber hose off the OUTLET end of the valve, with the machine in the OFF position or better yet UNPLUGGED (water and electricity do not mix, and can KILL you) ,and see that there is not a continuous flow or trickle of water. If there is any flow of water, in this scenario, then you have a bad inlet water valve, and the valve should be replaced rather than attempting to repair. Be sure to reconnect the rubber hose to the inlet valve before plugging the machine back in and attempting to run the machine, or you will have a high pressure flood, and likely electrical shorting under the machine which could likely ruin the machine.

Dec 30, 2011 | Whirlpool GU2400XTP Built-in Dishwasher

1 Answer

We bought a new dishwasher because the old one wasn't draining all the way. Same problem with the new one?

The pump is a motor which runs in one direction to spray water in the dishwasher to clean and the opposite direction to drain the water. The problem could be from a clog or kink in the drain hose. Several years ago the drain line would connect to the sink garbage disposal. If the garbage disposal is not draining or the dishwasher connection to the garbage disposal is restricted or clogged the dishwasher will not drain. Under the sink, look at the garbage disposal to see if a rubber hose is connected at the side of the disposal unit. If a hose is connected to the side of the disposal, remove the hose clamp and check for any restrictions from garbage in the inlet or hose. You can use a screwdriver to clean the fitting to the garbage disposal and a wire hanger to free any restrictions in the hose. If the dishwasher does not connect to the garbage disposal it should connect to the sink trap. This is more common with new dishwashers because they have built-in disposals. Disconnect the drain hose from the sink trap and the dishwasher and look for a clog at the sink connection. The dishwasher inlet should have an angled piece of plastic or metal facing downward to prevent the waste from the dishwasher from spraying up into the sink. Do not get to aggressive with the cleaning in order to prevent breaking the angled piece of plastic or metal. Look for any kinks in the hose and try to run water through the hose, but do not use the sink which you removed the drain line from or it could leak under the cabinet. If you see a bad kink replace the hose with a new one. I hope this works and you find the problem without a great deal of time or trouble.

Nov 22, 2010 | Whirlpool GU2400XTP Built-in Dishwasher

1 Answer

Fills arbitrarily not holding any water after a full cycle. All seems well and on any given day it will have filled without warning and floods floor

Check your drain hose to where it connects under the sink. If it is connected to the garbage disposer, and not looped upwards before it runs back to the dishwasher, it may just be drain water from the sink running back to the dishwasher. Even if it hooks up to a "t" spout under the sink, and the drains run a little slow, water can still run back to the dishwasher. The ideal set up is to have it connect to the drainage, run up behind the bowls of the sink, and then back to the dishwasher.
If this is not the answer, then you may have a defective fill valve that is allowing water to seep into the machine (very unusual in dishwashers). Also note that water valves require 23 psi of pressure to seat closed and if the incoming pressure is less than that, even a new valve may have the same issue.
Good luck and let me know how you make out, and if you have any other questions.

Jun 28, 2010 | GE 24 in. GSD4030Z Built-in Dishwasher

1 Answer

Dishwasher overflowed, garbage disposal still works. Ran the dishwasher and noticed food and debris shooting back into sink thru garbage disposal. Water was on floor. Upon completion of full cycle, water...

Before loading into the machine you have to remove food particles. Washer will wash the greasy surface. If particles are left in the dishes, the same will find entry to the drain system. Check the drain filter in your machine. Clean them. Mostly problem will be solved!

Apr 08, 2010 | GE 24 in. Profile PDW9880JSS Built-in...

1 Answer

DIshwasher drains at the top of the sink? How do I fix?

Sounds like the drain hose is blocked and it's using the overflow like it should. Take the hose off and flush it.

Mar 27, 2009 | GE Nautilus 24" Built-in Dishwasher

1 Answer

Hello my dishwasher will not drain after wash.

  • Check sink drain and drain hose for restrictions
  • Unjam the motor
  • Unjam the pump
  • Check the drain valve
  • Check the drive belt
  • Test the timer motor
  • If you have a brand new dishwasher or garbage disposer, check the knock out plug on the garbage disposer.

Jan 12, 2009 | Dishwashers

1 Answer

Kenmore Ultra Wash III Dishwasher will not drain properly

Fixerfailure, is the knock-out plug still inside if the garbage disposal inlet?

Stick a screwdriver in there to make sure.

spazmo1969, could be the rubber flapper is broken off in the pump discharge outlet.

Dec 27, 2008 | Kenmore 24 in. 15932 Built-in Dishwasher

1 Answer

Main sink and d/w did not drain. Used plunger heavily. Did not work. Had main line jetted out. Now sink drains but d/w still does not. Older model Kenmore #1661590 Thank you

Hello playultimate,
I am assuming that your dishwasher drains either directly into your sink or through a garbage disposal as part of your sink. Regardless of which method is used, you need to verify that your dishwasher drain system is funcioning properly so.. make sure your dishwasher drain filter is free from debris.. if you are still having a problem could be the pump is defective or clogged with food byproducts, the lines into and out of that pupm are clogged of the drain hose itself is clogged or pinched.. Once you have cleaned your drain screen inside the dishwasher, .. try cycling it withour dishes to see if you get a reasonable drain flow .. The key is to identify if its a clog/restriction or a bad pump... Hope some of these ideas will help solve your problem.. Get back to me if you are still struggling..

Dec 06, 2008 | Dishwashers

1 Answer

Kenmore Ultra Wash III Dishwasher will not drain properly

From the sound of things, your dishwasher drains faster than your sink drain ( via the garbage disposal) can drain it off.. You may have a problem with the way your sink drain/trap is vented and there is too much back pressure to drain down quickly.. When you run water from your sink, does it take a long time to drain down or if you fill your sink up and drain it, does it drain slowly ? That may be your problem.. Hope that helps.

Aug 26, 2008 | Dishwashers

Not finding what you are looking for?
Dishwashers Logo

4,429 people viewed this question

Ask a Question

Usually answered in minutes!

Top Tappan Dishwashers Experts


Level 2 Expert

75 Answers

Melissa Martin
Melissa Martin

Level 3 Expert

676 Answers

Trevor Turner

Level 2 Expert

183 Answers

Are you a Tappan Dishwasher Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides