Dishwasher air gap overflows, plumbers stumped

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  #1  
Old 06-30-07, 11:35 AM
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Question Dishwasher air gap overflows, plumbers stumped

When our dishwasher runs, water comes out of the air gap and leaks out onto the counter. This has been happening since we moved into the house a couple of months ago. It's a fairly new house (1999), and the dishwasher is a high-end Miele model.

The amount of water that leaks out is not a huge amount... maybe 1 or 2 cups. I don't think it's the whole amount of water used by the dishwasher.

We had our handyman look at it, he seemed confident at first that he could fix it. He checked the seal of the air gap and decided it was good. So then, he snaked out 20 feet or so of pipe assuming there must be a clog. But there was no clog. He gave up, stumped, and recommended that we call a plumber.

So, we called the plumber. He spent a couple of hours working on it, snaking through even more pipe (50 ft? Longer? Can't remember.) No blockage in the pipe. He also checked the air gap itself and decided that it looked fine (no cracks, etc.) He charged us > $300 and said "sorry, I can't figure out what's going on" and left.

Now, we're back where we started except poorer. We don't have the money to keep calling plumbers out and paying them $300 a piece hoping someone will eventually figure it out. So I'm hoping someone here might have an idea to help us.

One idea my wife has is that maybe the construction of the air gap doesn't quite have enough space to deal with the high pressure drain from the Miele dishwasher. Is this a possibility? Other ideas?

Thanks for any help!
 
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Old 06-30-07, 12:18 PM
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Have you tried asking a Miele service person?

An air gap is a pretty simple device and the only reasons I can think of for this to be happening is a too-small drain from the air gap, which should have been cured by the plumber, or that the air gap device itself is too small for the Miele dishwasher.

I don't know about Miele dishwashers or the requirements for an air gap on one. It is possible that Miele requires a special (oversized) air gap on their machines.
 
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Old 06-30-07, 12:31 PM
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just asking here but;

when you refer to the air gap, are you referring to the drain pipe of the washer to the house plumbing connection?

I can think of a couple reasons you may have this problem.

1. the washer empties faster than the house plumbing can accept it. (not likely)

2. the reciever of the gap does not allow a high enough head to push the water through the trap initially and you have an overflow until the water begins to flow. Since you have an air gap, there is no pressure to force the flow other than gravity so if the stand pipe is very short combined with a fast flow into it, you may get a temporary "restriction" effect.

3. a clogged vent. depending on how the plumbing system is built, I can see where this may cause a slight pressure build up on the other side of the p trap and cause the same situation as #2.

It seems more and more homes are using those small undercounter vents (plumbers! what are those correctly termed?) which incorporate a rubber flap to seal which could be subject to sticking, which would cause a pressure build as suggested until there was enough pressure to make it breathe.
 
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Old 06-30-07, 01:01 PM
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The typical sink deck mount air gap (the kind that are round chrome cylinders that mount in the 4th cut-out hole) are subject to the workings of a design that heavily rely on a baffle inside. If anything is wrong, the water flow can get past the baffle a little and come out onto the sink deck, as you state.

Also, the discharge lines (often black rubber heater hoses) are not that big an i.d. and every tube must be totally clean inside and this other baffle in the drain's tailpiece extension must be clean also, as does the inside of the airgap.

Another type of airgap system would never have this problem as they construct it building it identical to the washing machine standpipe design which is 1 1/2 inch i.d. throughout. The smaller o.d. dishwasher hose then simply gets hung inside the top of the standpipe and is secured at the cabinet wall with a u-clamp to prevent the hose from flying out of the standpipe during discharge. This standpipe also will have it's own trap. Like I said, it looks just like a washing machine standpipe.
 
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Old 06-30-07, 05:30 PM
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Hi. Look under the sink an air gap has two hoses connected to it a big one goes to the washer and the smaller one goes to the garbage disposal or tail peice. The small hose plugs up and causes the problem you have. At the top of the sink pull the cover off the air gap under that is a cap that snaps in place remove that and run a wire down the little hose ( I use a piece of solid electric wire)Then I pour water down the hose to clear it.
Good Luck Woodbutcher
 
  #6  
Old 06-30-07, 05:35 PM
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The discharge of an air gap should be 7/8" ID hose, as short as possible, not kinked, not bellied (has downhill pitch for it's entire length), and clear of any debris or obstruction.

Air gaps are not required in many places. Where they aren't, the drain hose is looped as high as it can go in the cabinet (and strapped there) before entering the garbage disposal or branch tee. Check with your local building dept.

When I run into a 'problem' air gap, I'll replace it with a copper air gap, which seem to work better. If you can find a copper air gap and replace the 7/8" hose, it won't cost much or be very difficult, and may solve the problem.
 
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Old 07-01-07, 11:50 AM
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~and~

...if the DW is draining into a GD, check to make sure that the opening in the GD is completely clear. They come from the factory with a knockout plug that is removed for the DW drain.
 
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Old 01-09-11, 02:49 PM
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Chronic air gap problem

I purchased a new home in 2000, and after several years, water began spewing from the dishwasher air gap. We let this go for a long time, but when the garbage disposal broke, I purchased a much better one and installed it myself. I knocked out the plug, and installed the connections as they were previously. Although I did not expect the result, there was suddenly no more problem with the air gap. I looked at the old disposal, and it appeared that part of the plug had not been properly knocked out. However, after several months, the air gap began doing the same thing. Additionally, there was now water flowing down the OUTSIDE of the tube from the dishwasher to the air gap whenever the diswasher drained. This caused a large accumulation of water beneath the sink. I just took apart the whole thing and put new clamps on all of the hoses. There was no obvious obstruction in the dishwasher drain hose, nor was there any with the disposal hose attached to the air gap. The leak has been adequately fixed, but there is still a huge quantity of water coming onto the counter every time the diswasher drains. I also could not see any obvious blockage within the air gap, but I'm now at a bit of a loss how to proceed. Could there be a problem at the level of the dishwasher?

Any help would be appreciated.
 
  #9  
Old 01-20-11, 09:12 AM
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Exclamation

A common situation with the Air Gap is no fault to the Air Gap itself. It has no moving parts to wear out.

2 things become obvious when they start to leak in an area not designed for water flow, but for the ability to pull air from the free atmosphere and interrupt the path of wastewater so it cannot reverse into the dishwasher, causing physical harm or injury or sickness.


1. Black 7/8" dishwasher hose is building up/narrowing inside the piping from Air Gap to barbed nipple on the garbage disposal or tapped tailpiece

2. Debri buildup right at the connection where the pipe connects to the barbed nipple inside the black flexible tubing

3. Black flexible tubing is not cylindrical in nature, or kinked causing an ability for debri accumulation to occur

4. Barbed nipple on a tapped tailpiece (not garbage disposal) is 5/8" instead of 7/8" and it'll cause resistance every single time and not work.


It's important to know that these equations where water is backing up through an Air Gap, it mostly ties into the end user and how they use their dishwasher. If you do not even take the simple effort to wash off the majority of food debri before setting in the racks, you'll have the above problems constantly.

That's why I as a plumber run into these situations, can work for one customer that's had a dishwasher/Air Gap/disposal setup for 25+ years and it looks almost as clean as it was first installed,

to the customer in a brand new house not even 2 years old and it looks like the same setup above is moving more solid waste than liquid waste in the piping equation.

I'm not going to complain because I'm earning a living off that misuse of the plumbing system and telling them never stops them, so I do the job and say thank you.


An Air Gap will never go bad. Cosmetically in finish, yes. But not in functionality. If the end user doesn't make a habit of precleaning dishes/utensils, things will always go wrong in that equation.
 
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Old 01-20-11, 06:36 PM
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Originally Posted by DUNBAR PLUMBER View Post
...It's important to know that these equations where water is backing up through an Air Gap, it mostly ties into the end user and how they use their dishwasher. If you do not even take the simple effort to wash off the majority of food debri before setting in the racks, you'll have the above problems constantly….
hi folks.

DUNBAR PLUMBER I wonder if the dishwasher manufacturers have a lot to do with the problems? I installed a brand new Kitchenaid about seven years ago. Here is what my manual says:

“…Remove leftover food, bones, toothpicks and other hard items from the dishes. To conserve water and energy and save time, it is not necessary to rinse dishes before putting them into the dishwasher. The wash module removes food particles from the water. The module contains a chopping device which will reduce the size of food items….”

But I always pre-clean the dishes and utensils but feel somewhat guilty in doing so. Early on with the DW I ran a few tests and found that if I leave some things stuck to the dishes the dishes come out with the food still stuck on them. So I just got in the habit of always rinsing them clean and not trying to figure out whether this dish or that dish needs to be rinsed. But maybe that’s a waste of time and water?

But I’m wondering if the other folks here let the dishwasher do what it’s supposed to do according to their manual and not rinse them off squeaky clean like I do? Sounds like you should rinse them first.
 
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Old 02-05-11, 06:54 PM
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I just remove most large particles of food from dishes before I run them through the dishwasher. I don't rinse them squeaky clean, and our dishwasher gets the dishes completely clean.
 
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Old 02-06-11, 09:12 AM
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hi cory -

Sounds good. What brand DW do you have? The biggest problem I remember was with spaghetti sauce that I intentionally let dry and harden for the first test for the DW. The DW didn't budge it. I thought Kitchenaid was supposed to be pretty good, but might just be a myth.
 
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Old 02-06-11, 02:41 PM
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It's a Frigidaire dishwasher. I have only found one, maybe two dishes that didn't come out clean, and that was from dried egg yolk.
 
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Old 02-07-11, 05:24 PM
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Originally Posted by crazycory22 View Post
It's a Frigidaire dishwasher. I have only found one, maybe two dishes that didn't come out clean, and that was from dried egg yolk.
thanks cory. I'll look into a Frigidaire next time. I did hear before that in fact they are pretty good.
 
  #15  
Old 03-26-11, 09:18 PM
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Same problem here. Just figured out the problem...kink in a new drain hose the plumber installed. It turns a corner to sharply to go to the garbage disposal, causing the water to be stopped---and out through the overflow vent!
 
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Old 03-28-11, 09:12 AM
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Isn't that something? That sounds like a bad and obvious mistake even for a newbie to make, let alone a real plumber! Guess maybe some of these guys are just rushing too much today and are getting very careless.

But those are the kind of solutions you like - real easy and zero cost.
 
  #17  
Old 08-12-11, 10:19 AM
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I have the same problem, but I took the extra step of disconnecting the air gap from the drain hose to the GD. I still have the same problem: water pours out the top and trickles out the bottom. Water pressure going to the air gap has to be the problem (this is the third air gap this has occurred with). Does anyone know enough about dishwashers for me to try to fix this myself? Or is this a "I need a new dishwasher" sort of problem?
 
  #18  
Old 08-13-11, 05:07 AM
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Assuming the drain lines have been checked and are clear, my solution would be to eliminate the air gap. Just run the dw drain hose straight to the house drain with a high loop attached under the counter.
 
  #19  
Old 08-15-11, 09:45 AM
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So...embarrassing as it is, I'm going to cop to it: the air gap was installed backwards, with the dishwasher connected to the large, angled stem and the garbage disposal connected to the smaller, straight stem. (In my defense, this is how it was hooked up when I bought the house.) Switched them around after a particularly helpful person at Home Depot corrected me, and now it's working perfectly.
 
  #20  
Old 11-05-11, 11:29 AM
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Thumbs up Air gap problem .......... i figured it out.

I had a similiar problem with my air gap. I installed a new sink and installed a brand new air gap with new hoses and everything. We hooked it up to the disposal and ran the dishwasher. I had lots of water spewing out of the air gap. My wife was not a happy camper... We disconnected the hoses and checked to see if the knockout was completely out and checked for any sort of food blockage. Everything was completely clear. Tried again and water came spewing out again.
I really did not know how the air gap worked so we took it apart. I noticed that what was going on in it was that the dishwasher was pumping the water from the dishwasher via pump using the smaller diameter hose, but then that water would hit the inside of the air gap and then fall into the other larger diameter hose inside the air gap and flow via gravity to the drain hole in the disposal. So I realized that the water flow as it left from the air gap was entirely gravity forced.
My solution........ my hose ("7/8 larger hose) was hooked up to the airgap on one end and was too long so it dropped below the level of the drain connection in the disposal so the gravity fed water was having to go down the hose and then back up the hose to be drained. It was loosing momentum having to go back up the hose, so it could not drain properly. I cut the hose and made sure it was a straight shot with no dips to the drain hole in disposal and hooked it up again. It works perfectly now.
So the old adage for plumbing, $&#% runs downhill. Well, it worked for me. I am not a plumber, but we figured it out!!
 
  #21  
Old 12-21-11, 04:43 PM
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Moved into a 1973 house with existing dishwasher that didnt work. Bought new dishwasher and installed it, but AIR GAP WAS OVERFLOWING like crazy. So i read dozens of forum articles about this issue. All had similar possible solutions, kinked hose, food blockage, garbage disposal plug not entirely remved etc. Surley, my existing garbage disposal "must"have had its plug removed by previous owner already right...??? RIGHT???

Moral of my story, don't assume anything. My garbage disposals plug was never even removed much less partialy removed by the previous owners. But they had the drain line hooked up to it. I wonder how long that went on for??
Maybe they were "OK" with the water spewing onto their counter?
 
  #22  
Old 12-23-11, 11:55 PM
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Originally Posted by B-Rady View Post
Moved into a 1973 house with existing dishwasher that didnt work. Bought new dishwasher and installed it, but AIR GAP WAS OVERFLOWING like crazy. So i read dozens of forum articles about this issue. All had similar possible solutions, kinked hose, food blockage, garbage disposal plug not entirely remved etc. Surley, my existing garbage disposal "must"have had its plug removed by previous owner already right...??? RIGHT???

Moral of my story, don't assume anything. My garbage disposals plug was never even removed much less partialy removed by the previous owners. But they had the drain line hooked up to it. I wonder how long that went on for??
Maybe they were "OK" with the water spewing onto their counter?

I had this very exact situation happen with a customer of mine. Granted, I do not work for this customer anymore because of their embarrassment regarding the situation.

I get called out for "Dishwasher Air Gap Overflowing" and I proceed to troubleshoot the situation.


A very quick trick to determine you have a straight through connection to your garbage disposal or tapped tailpiece:

Unravel a thin wired coat hanger and remove all sharp bends. Then proceed to curl over the end you're going to put through the Air Gap that follows through the 7/8" black hose that leads to the barbed nipple.

When I did this before removing the piping, I hit a dead stop at the disposal.

Customer installed a new garbage disposal 2 years prior. ???

So why did they call me?


The Air Gap was bellowing water from that vent cap into the sink, every-single-time the dishwasher ran. It was not until the wastewater that was escaping that very cap that was shooting over the sink onto the floor is when they called me.


These customers were in a situation where I wasn't going to lie about the knockout plug removal being the cure. The wife was highly embarrassed, the husband on the phone was telling a story that wasn't adding up.

For two years they had a waterfall of dishwasher wastewater shooting out of that vent cap into the sink, thinking that was normal.


We get calls for this situation randomly, usually the knockout is still intact.
 
  #23  
Old 01-14-12, 01:47 PM
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Red face This worked!

My wife complained about the air gap leaking water into the sink while the dishwasher was working so I figured it out and this worked great: I removed the 7/8" hose running to the garbage disposal and cleaned it out. It had a little bit of "gunk", but not much. I then noticed that the original plumber had connected the hose in a "U" shape so that the hose was forming a "trap". I then got a piece of wood, and cut a special piece about 5" long that held up the middle of the hose, so that there was no sagging or trap effect. Now, gravity allows the water to flow directly into the garbage disposal. The lowest part of the hose is at the garbage disposal, NOT half way there. If this doesn't work, try cutting the hose shorter to eliminate the trap effect. My wife told me I can do anything except get pregnant. Good luck!
 
  #24  
Old 01-15-12, 08:05 AM
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Really Liked My Frigidaire DW

To: zoesdad and crazycory22,
My first dishwasher came after 8 kids were gone from home and I was single! I bought a mid to higher priced Frigidaire and always liked it really well. I have seen dishes removed after cleaning from lots of friends' and relatives' dws and noticed that many of them just weren't very clean. I have a new Frigidaire sitting in my garage waiting to be installed when I finish my current kitchen remodel. I will certainly heed all of the experiences here as I'm installing it! Thanks to all!
 
  #25  
Old 03-29-12, 04:52 PM
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I'm done

Thanks to all on this forum. Deciphered the problem - my air gap was leaking also. with all the info posted on this forum, I had no issues getting the right parts, and fixing the hoising issues created by the original installer.
 
  #26  
Old 01-30-13, 11:43 AM
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Problem solved

Same problem as poster. The first problem was that they forgot to push the tab out in the garbage disposal when they installed the new one. But the airgap still leaked. This was solved by cutting off about 1.5 feet of hose that was going from the airgap to the garbage disposal. It was too long and was causing a 'trap' somehow.
 
  #27  
Old 04-15-13, 08:41 AM
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Air Gap overflowing solved

The whole problem was the air gap cap. I checked all other things as suggested by other posters. I fortunately had another dishwasher in the garage and switched the caps and it was solved. This is why: The caps I have are made of two pieces. The inside piece had slid up inside the outer shell. I could slide it back down but when it got hot, the outer shell expanded slightly and the inner slid back up again. When that happens the water is not redirected back downward but out the opening. So if you want to try the easiest fix first then get a new cap for a few dollars.
 
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Old 04-15-13, 09:31 AM
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Closing thread. The OP has not responded to this thread since 2007....
 
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