If the sink drain clogs, will an air-gap stop water in the sink from backing up into the dishwasher and flooding the floor?

I have seen the discussions about whether to install an air gap or not with a dishwasher, mostly not. The debate seems to revolve around an ugly appendage near the sink or if the dirty water will get sucked into the city water system.

I understand the whole high loop issue as that is how the old dishwasher was hooked up.

The difference with my question is that I am installing several thousand dollars of laminate flooring and I don't want to void the laminate warranty with a flood if it can be prevented by a relatively cheap air-gap device.

The granite counter is coming this Friday and I just found out about the air gap issue while looking at faucets. :eek:

We have had water on the floor around the dishwasher in the past with no apparent reason. The repair man found nothing wrong with the dishwasher. I did not suspect the high loop drain line issue until now. :confused:

I also see some home inspection sites debating the issue. It seems that they could write up the dishwasher if it does not have the air-gap device. :o

Hello Roger Wabbit,

Air Gap or No Air Gap - is a highly debated issue in this Forum. Some agree, some disagree. If your local Code calls for Air Gap than I suggest that you install one. Otherwise, use your own judgment. In any case, here is my response to your questions:

2.If the sink drain clogs, will an air-gap stop water in the sink from backing up into the dishwasher and flooding the floor?

Yes, if the drain clogs bellow the Dishwasher-to-Drain connection then it will prevent dish water from the sink emptying into Dishwasher. However, High Loop will prevent the same discharge if properly looped and attached to the under counter.

2. I have seen the discussions about whether to install an air gap or not with a dishwasher, mostly not. The debate seems to revolve around an ugly appendage near the sink or if the dirty water will get sucked into the city water system.

Need for Air Gaps is highly questioned in parts of the country where Air Gaps are not mandated by the Code. In some parts of the county, Air Gaps are required by the local Codes. Usually, once Homeowners learn about its functions and benefits, they usually don't object having one installed.

Presence or absence of Air Gap is unrelated to gray water being siphoned back into City drinking water supply system. This issue relates to check valve being installed on your Pull-out Spout hose.

3. I understand the whole high loop issue as that is how the old dishwasher was hooked up.

Yes, most of the old Dishwashers - and many new Dishwashers - are still installed with High Loop discharge

4. The difference with my question is that I am installing several thousand dollars of laminate flooring and I don't want to void the laminate warranty with a flood if it can be prevented by a relatively cheap air-gap device.

You can flood your floor with Air Gap installed and also without Air Gap installed. Both Air Gap and High Loop need to be properly installed to assure proper functionality of the discharge system. Moreover, kitchen sink drain and Garbage Disposer have to be kept clean to be able to accept discharging water without inhibition in flow.

5. We have had water on the floor around the dishwasher in the past with no apparent reason. The repair man found nothing wrong with the dishwasher. I did not suspect the high loop drain line issue until now.

Water on the floor and around dishwasher can be caused by a bad seal around the D/W door. Overflows through High Loop or Air Gap are rare.

6. I also see some home inspection sites debating the issue. It seems that they could write up the dishwasher if it does not have the air-gap device.

You are not stating your geo-location. In my area (So.California) it is Code violation not to have Air Gap installed. When it comes to a house pre-sale Inspection air gaps installations are always check. If there is missing air gap than the house will not sell until new air gap is installed by a licensed plumber.

Hope that will help... Good luck with your project ! Milo

" will an air-gap stop water in the sink from backing up into the dishwasher and flooding the floor?

" yes a gap will stop the water from going back into the dishwasher. It will dump on your counter top and then flood the kitchen

Quote:

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Originally Posted by ballengerb1

yes a gap will stop the water from going back into the dishwasher. It will dump on your counter top and then flood the kitchen

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Nonsense.

Nearly every DW air-gap leak I've ever encountered can be traced back to shoddy installation practices.

The usual suspects are:

Stressed hose connections which pull down on the air gap assembly and cause the top to pop off.

Cross threading the top portion of the assembly.

Or installations on counter tops that are too thick to allow for proper tightening of the top portion of the assembly -- The fix for this is to order a deeper throated air-gap assembly.

Truth be told, I'm not a big fan of counter mounted air-gaps, which is why I generally opt for a Johnson Tee when the conditions are right for one (DW is on an exterior wall), but more and more homes are placing DW in island locations which pretty much precludes the use of a Johnson Tee.

>shrugs<

As I said, I'm not a big fan of 'em, but I did witness an event this last November that convinced me they are a necessity -- I watched the water squirt out of a counter mounted Air-Gap when my Sister dropped a frozen turkey into a full sink compartment two days before Thanksgiving; The sudden change in pressure popped the disposal drain plug and sent the contaminated water up a foot and a half of "7/8 rubber house and out the top of the air-gap -- Had this been a high loop, the contaminated water would have gone down the "5/8 discharge hose and into the sump of the DW -- A DW full of recently cleaned dishes that 30+ guests would be eating off in two days time.

I know this whole Air Gap/High Loop drama has been done to death in this forum over the years, but seriously, would it kill you and the rest of the posters/Experts in this forum to be advocates for code compliance?

I see a lot of things posted in this forum that I dislike, sometimes mightily (hence my scarce input), but I still do my very best to take the OP's prevailing code into mind when I formulate an answer.

Poster said his sink drain clogged and backed up into the washer. I was saying adding an air gaps will just change where the water is going to dump into the kitchen. An air gap is not the fix for a clogged sink drain which is what he has. He needs to think less about an air gap and get in there and rod the drain.

Bottom line! Counter top air gapos can fail . High loops don't!
Good luck, Tom