I have had the usual symptomatic water overflow out of the dishwasher air gap on the top of my sink countertop. After replacing the countertop with granite and relocating the air gap hole, I replaced the hose from the air gap to the disposal and insured there was no blockage in the disposal and new hose. Yet I have so much water pressure coming from the dishwasher that it shoots out of the air gap vent. I confirm the water is draining into the disposal from the air gap vent but it seems there is so much water or the pressure is so great the system can't handle the amount of water being discharged and backs up into the air gap. I've even looped the extra amount of hose from the dishwasher to the air gap above the disposal drain height to see if that would solve this. It did seem to take some of the pressure off of the water coming out of the air gap but it still spews out. After searching and reading all the posts regarding this usually common issue, I'm at a loss. Anyone have any ideas?

letmetellu

In our code book we have to install an air gap, and I do not agree with the notion that you don't need one to prevent back flow into the dishwasher. If a doit-yourselfer has a stopped up sink and his friend tells him to fill up the disposal side of the sink with water and stop up the other side of the sink and then turn on the disposal, Where do you suppose the water is going to go, with all of the contaminates that have collected in the disposal and the hose leading from the dishwasher.

letmetellu

After all of the things that you have tried I think I would go to the hardware store and invest in a new air gap, they come in different designs and it could be that there is a problem with your's and a new one might stop the problem.

One thing I will mention but I am sure that you have checked is to make sure that there is not kink in the 7'8 inch hose from the air gap to the disposal, also make sure that the 7/8 inch hose has a downward slope all the way to the disposal.

daveskee

I've replaced the old air gap with two different types and same result. No kink and the 7/8" hose is downward sloped. Already addressed these. Any other ideas?

ballengerb1

Sorry Dave but I've run out of ideas and it isn't feasible to swap out a dishwasher to try another. Seems like you've done everything else. I'm sure the dishwasher people won't like this idea but you could try reducing the drain tube between the machine and the air gap. Try partially crushing the drain hose with a C clamp to see if it fixes your problem and doesn't create a new one.

speedball1

"If a doit-yourselfer has a stopped up sink and his friend tells him to fill up the disposal side of the sink with water and stop up the other side of the sink and then turn on the disposal, Where do you suppose the water is going to go?"
With a air-gap it's gonna go all over the counter top and kitchen floor. That's where.
And what idiot would advise anyone to pour more water in a clogged sink and then attempt to use a disposal to clear the clog. I have been putting in dishwashers in condos and new houses since 1979 using a high loop instead if counter top air gap. In all those years, and in the hundreds of installations we have done, we haven't had even one complaint about a high loop misfunctioning.
I KNOW that the air-gaps can't make that statement because we get complaints about counter top floods from time to time here in the plumbing page.
LetmetellU, perhaps you and Growler are forced, by code, to use counter top air-gaps but here we have a classic case of mechanical versus natural. Sort of like "What is more likely to fail?" A regular vent out the roof or a AAV?
A high loop or a counter top air-gap? In my area we have a choice. We went with a high loop. I rest my case. tom

iamgrowler

Sure -- And without the air gap it's going to go right into the hose and then down the hose and contaminate the dishwasher.

I hate to break it to you, Tom, but your reply was almost verbatim the example I give during class for why an air-gap is required under the UPC.

I'm not going to get into a pissing match with you over which code is superior over the other, but I think it should be noted that it was you who illustrated the point.

You're kidding, right?

Think back on all of the truly bad advice you've left negative feedback on, Tom.

Y'know, I've yet to encounter the situation you describe in a properly installed air gap.

Usually if the air gap has failed, it is because the user failed to rinse the dishes off or the limiter on the discharge pump has failed.

Sure -- But your example contaminated the dishwasher and the dishes in the dishwasher (something the user couldn't possibly be aware of), while the other example merely flooded the counter top and kitchen floor (the user would have to be deaf, dumb and blind to not figure out there was a problem if this should happen).

speedball1

Great rebuttal Growler. Good points all! One problem. Would you care to check back on the complaints we have got on air-gaps versus high loops? Gee! That's correct!! We haven't got any high loop complaints have we? You're correct about the disposal pumping gray water back into the dishwasher if some fool were to advise clearing a clogged drain line by filling up the sink with water and turning on the disposal. Let's see how many complainbts we have got over the years on that scenario. Oops! Can''t find any of those either. Even if the drain line were cloggec and standing water in the tub it still wouldn't drain back into the DW unless some total idiot ran the disposal. I can only repeat, "here we have a classic case of mechanical versus natural. Sort of like "What is more likely to fail?" A regular vent out the roof or a AAV?
A high loop or a counter top air-gap?, (This is a no brainer) In my area we have a choice. We went with a high loop. I rest my case."
I was impressed. While your rebuttal was great and you took it point by point the very complaints and posts by askers prove that while your concerns and arguments sound valid they don't hold up when you check back on askers complaints of the same nature. However, I enjoyed your reply. Have a great week end ! Tom

letmetellu

I think that anyone that would call the water in a stopped up disposal, the nastiest household fixture in the entire house, even nastier than the commode, gray water is an idiot.

speedball1

First of all thanks for calling me a idiot. Now, just what's the discharge from tubs, showers, lavatories, washers and kiutchen sinks called? Gee! Whadda ya know! It's called "gray water" as per against "fecal matter". I would be most interested in your name for it. In the meantime if you're gonna insult someone and call him a idiot get your definitions correct before you do it or you might end up looking like one yourself.

labman

Perhaps whoever coined the term ''gray water'' for the discharge from sinks, showers, etc. was an idiot, but it is a common term for it. I wouldn't call a highly trained, experienced professional an idiot for using a common term. Those that persist on calling people idiots on AMHD can become former members.

I like the idea of restricting the flow from the dishwasher. It would have been my first suggestion. The C-clamp will be a good first try. Before selling the house, you may want to put something inside the hose or pump outlet out of view. I never have posted much to plumbing because when I came here, Tom was posting better answers than I could.

You do want to fix it. In many cases a problem is still yours after you sell the house.