Seattle Home Inspector's Blog


Dishwasher air gap device as “water-feature.”

It is not all that unusual to turn the dishwasher on and have water come out of the air gap device---such as this one where the hoses were hooked up backwards. 

air gap fountain

This condition is immediate and is obvious as soon as the dishwasher starts to drain the first time.  It usually only occurs in new construction or newly installed dishwashers.

The other day I had one in a newly remodeled kitchen back up out of the air gap device at the middle of the draining cycle instead of at the beginning.  It was as if the drain could take some water for a while and then it would gradually back up the hose and out the air gap device. 

The reason for this was because the drain between the air gap device and the disposal connection had a BIG loop in it.  This loop held water and continued to hold water even after the washer was done. 


Water can only drain by gravity through this section of pipe because the air gap device represents a break in the drain.  Prior to the air gap device the drain is under pressure.  Because the water cannot drain by gravity, eventually the amount of water being pumped into the air gap device exceeds what can drain by gravity through the drain that is full of water.

Water filled drain from air gap device


This is a pretty simple fix and is accomplished by installation of a drain from the air gap device to the disposal that does not trap water.

Proper location of drain from air gap device

Charles Buell, Real Estate Inspections in Seattle.


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Comment balloon 58 commentsCharles Buell • February 22 2012 06:19AM


I can not ever recall seeing an air gap installed on a dishwasher here. 

Posted by James Quarello, Connecticut Home Inspector (JRV Home Inspection Services, LLC) over 6 years ago

I've never seen water come out of the air gap before. I think it'd shock me at first, then be pretty funny.

Posted by Eric Michael, Metro Detroit Real Estate Professional 734.564.1519 (Remerica Integrity, Realtors®, Northville, MI) over 6 years ago

In all my years I've never seen water shoot out of an air gap.  Just goes to show you can learn something every day.

Posted by Ralph Janisch ABR CRS Broker, Selling Northwest Houston to good people like you! (Janisch & Co.) over 6 years ago

Makes you wonder what the "professional" who installed the dishwasher was thinking when you so easily found the solution to the problem.

Posted by Kathryn Maguire, Serving Chesapeake, Norfolk, VA Beach ( (757) 560-0881) over 6 years ago

You always walk us through these issues and repairs so well...easy to understand...thanks !

Posted by Kristin Johnston - REALTOR®, Giving Back With Each Home Sold! (RE/MAX Realty Center ) over 6 years ago

Charles, If you could get a little plastic cove that looked similar to a cherub that could be a great feature.  

Posted by Jack Gilleland (Home Inspection and Investor Services, Clayton) over 6 years ago

I have found that this is more likely caused by the "knock out" in the garbage disposal has not been removed. The "know out" is a metal plug in the dishwasher drain attachment that needs to be removed before installing the dishwasher drain line. This can be done very easily by first removing the drain line then placing a screw driver in the drain hole and hitting the handle end of the screwdriver with a hammer gently a couple of times, then replacing the drain hose. Remember to reach into the disposal and retrieve the metel slug BEFORE running the disposal.

For safety, unplug the disposal before starting this procedure!

Posted by Don Gockel, Realtor, Broker, GRI - Antelope Valley Real Estate (NextHome The Gockel Group - Palmdale Lancaster Quartz Hill -) over 6 years ago

Hi Charles - Good information and a great title to this post!

Posted by Susan Neal, Fair Oaks CA & Sacramento Area Real Estate Broker (RE/MAX Gold, Fair Oaks) over 6 years ago

Love the title of this post as a water feature...even inspectors are in on adding "fluff" now.  Perhaps just removing the disposal would be best. 

Posted by Heather Littrell, ABR,GRI,SRES Cabarrus County NC (Keller Williams) over 6 years ago

Charles love your post and comments. I just had a new sink and dishwasher installed by a master plumber who didn't use the air gap device. Said it was not necessary...

Posted by Richie Alan Naggar, agent & author (people first...then business Ran Right Realty ) over 6 years ago

This just started happening to me after I installed a new garbage disposal.  I will now attempt to fix this myself.  Wish me luck and THANK YOU for the timely post!

Posted by Allan Sanchez, Rocklin & Roseville, Short Sale Agent (Roseville CA & Rocklin CA Short Sale Agent) over 6 years ago

What a coincidence... just light night i was draining a pool of standing water out of my dishwasher and spaghetti out of my air gap.

Posted by Melissa Zavala, Broker, Escondido Real Estate, San Diego County (Broadpoint Properties) over 6 years ago

I had a "water feature" in my laundry room, turned out it was from the upstairs toilet....yep, mold and all. Ugh.

Posted by Karen Fiddler, Broker/Owner, Orange County & Lake Arrowhead, CA (949)510-2395 (Karen Parsons-Fiddler, Broker 949-510-2395) over 6 years ago

Charles -- this can be less of an issue when there are two sinks and the sink without the disposal is where the water drains from - then you only get a problem with the drain line is plugged.

Posted by Steven Cook (No Longer Processing Mortgages.) over 6 years ago

this is just hilarious!  I have never seen it but how in the heck did they miss it!  I guess they never did a "test" run!

Posted by Jo Olson, HOMEFRONT Realty @ LAKE Roosevelt - Stevens County (HOMEFRONT Realty) over 6 years ago

Hey James, your jurisdiction may not require an air gap system on a dishwasher, some areas allow a simple high loop drain which will break the anti-siphon issue and prevent contaminants from the sink drain from back flowing into the "Lower" dishwasher drain and tub area, (Unhealthful Condition).

Air gaps have a secondary benefit in that if the drain line becomes obstructed at the disposal side, water can enter the sink via the counter top mounted discharge. With fixed lines and or a high loop system leakage can occur at the cabinet and cause damage.

Posted by Will Handley, Certified Master Inspection Services (Progressive Inspection Service) over 6 years ago

Hi Eric;

Leaks at air gap valves are quite common, I find them every week. The valve can become worn or debris can collect in the drain line or valve. I find it a lot when a disposal has been replaced and the side discharge plug was not removed prior to installation.

Posted by Will Handley, Certified Master Inspection Services (Progressive Inspection Service) over 6 years ago


Your Master Plumber maybe correct. Some high end newer dishwashers have built in air gaps. It's also possible that a proper "High Loop" drain line installation is proper and acceptable in your area. I think the true lesson of this post is if an air gap valve IS present, properly installed and serviceable it should NOT have water discharge per the visual above...

Posted by Will Handley, Certified Master Inspection Services (Progressive Inspection Service) over 6 years ago

Excellent post Charles! Thank you for the information and discussion of just one of many important issues that can arise during a home inspection..

Posted by Will Handley, Certified Master Inspection Services (Progressive Inspection Service) over 6 years ago

New construction just today - the dishwashwer drain looped twice (that's two times) UNDER the disposal!  Once I had a realtor on an inspection see water coming from the air-gap device and said, "You mean it's not supposed to do that?"

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 6 years ago

Charles - I reported the SPAM - Comment #20.

You did a great job with your explanations as to why this happens.


Posted by Carl Winters over 6 years ago

we don't typically see air gaps installed on dishwashers... most of the machines that are installed here, already have a built-in air gap.

Posted by Alan May, Helping you find your way home. (Coldwell Banker Residential) over 6 years ago

Hi Charles~Now that's something that I've never heard of before. Congrats on the feature!

Have an AWESOME day!

Posted by Michael S. Bolton, MN Appraiser (Michael S. Bolton,Inc.) over 6 years ago

Jim, I know it does vary from area to area around the country

Eric, it is indeed hysterical when you see it become a fountain :)

Jeane and Ralph, while not an every day occurance I see it a couple of times a year

Kathryn, on this one I actually did have to scratch my head a bit.

Kristin, thanks, and you are welcome---glad you find the information useful

Jack indeed indeed :)

Don, I agree that is sometimes the case and was one of the first things I checked with this installation.

Susan, thanks

Heather, but the dishwasher would still need some place to drain too :)---it wasn't the disposal's fault.

Richie, regardless of what the plumber said they are still a good idea.  In some jurisdictions, like Seattle, they are required regardless of the newer ones that have them supposedly "built-in" to the dishwasher itself

Alan, one of the first things to check is to make sure the disposal has not plug in it and that there is no loop to trap water in the drain from the air gap itself.

Melissa, you gotta love the ole spagetti in the air gap trick :)

Karen, ouch---not a good kind of water feature for sure

Steven, so you are one vote to keep the water feature? :)

Jo, not long enough that is for sure

Will thanks for your additions to the discussion.  I am not a big fan of the high loop for the reasons you mention and even though they are allowed by some jurisdictions I still don't think it is best practice---the loop under the countertop can never qwite get above the flood rim of the sink.

Jay, you gotta love comments like that :)



Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 6 years ago

Carl, thanks----and I reported the spammer too---always good for 10 free points :)

Alan, they will still function better with one and many jurisdictions still require them even on the washer that have the "built-in" ones.

Michael, thanks---it seems like I get features when it is the most difficult for me to respond to comments :)

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 6 years ago

At our walk thru, I asked the builder where our air gap was, and the builder looked at me like I was crazy. As I show houses, none of them have them here in Austin. I don't understand...

Posted by Donna Harris, Realtor,Mediator,Ombudsman,Property Tax Arbitrator (Donna Homes, powered by JPAR - over 6 years ago

Hey Donna, next time you're in one of these homes without an air gap visible, look under the sink at the dishwasher drain line off the disposal. If it's a high loop installation the visible line should leave the disposal and immediately head up towards the top of the cabinet. We're hoping it gets above the sink rim and then it should begin a downward descent towards the dishwasher, (You'll lose sight of it as it goes through the cabinet wall).

If you don't see a high loop or air gap, one of two things are possible. #1 the dishwasher if newer and fairly expensive can have a built in air gap. #2 the system is incorrectly installed and of course presents an unsafe and or unhealthful condition with regard to sink drain cross contamination. 

You'll start to be a little more comfortable with your decision once you've seen a few...

BTW, here's a picture of an air gap hanging loose below the counter top at the sink cabinet - (Leakage can cause damage).

Air gap improperly located at sink cabinet

Posted by Will Handley, Certified Master Inspection Services (Progressive Inspection Service) over 6 years ago

Hi Charles, I have never even heard of an air gap before reading this post. Never in Florida, Georgia, or Virginia, or any other city I have ever visited have I seen or heard of such a thing. If you have them, how can we not have them??


Posted by Sharon Alters, Realtor - Homes for Sale Fleming Island FL (Coldwell Banker Vanguard Realty - 904-673-2308) over 6 years ago

Donna, your question has no "easy" answer.  There not being present can be do to ingnorance, arrogance, or in some case due to not being required.  Sometimes it is because the codes are not being enforced.

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 6 years ago

Sharon, please see my previous comment to Donna.  They have been around for a very long time---why you are not seeing them at all is surprising, but I have learned that things can vary widely around the country and some areas are slower to adapt newer requirements than others and are enforced more unevenly as well.

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 6 years ago

Here's a quick youtube video that will give us a little visual help...;f=2;t=002647

Posted by Will Handley, Certified Master Inspection Services (Progressive Inspection Service) over 6 years ago

I think I'm going to change mine to work like that. Who doesn't like a water feature.

Posted by Rob Ernst, Reno, NV-775-410-4286 Inspector & Energy Auditor (Certified Structure Inspector) over 6 years ago

Never used in Illinois, at least central Illinois as far as I see. I do see the loop installed by the local Big Box crews entering the sink base at the floor level. Somethimes they even have the hole for the loop hose at the counter level, but still install at the cabinet floor level. Go figure.   

Posted by Scott Seaton Jr. Bourbonnais Kankakee IL Home Inspector, The Home Inspector With a Heart! (SLS Home Inspections-Bradley Bourbonnais Kankakee Manteno) over 6 years ago

We have the high loop drain line the problem we sometimes see is they don't high loop so no anti siphon.

Posted by Surprise Arizona Realtor Jim Braun Sun City Grand Active Adult Communities, Surprise AZ real estate Phoenix West Valley (Coldwell Banker Residential Brokerage Jim Braun Sun City Grand Az ) over 6 years ago

i wish more inspectors would be like you ....  so logical and less over-dramatic.  


Posted by Angela Shopper (Wingman Realty, LLC) over 6 years ago

I just love these Mr. Fix-It posts.  They are great tidbits of info that might make us a hero to the client.

Posted by Warren Moore, CRS, GRI (Warren Moore Real Estate) over 6 years ago

Will, thanks for the additional information

Robert, we could start a whole line of decorative caps---frogs, peeing cherubs etc :)

Scott, the biggest problem with the high loop is that because it usually can't get above the flood rim of the sink a flooded sink (plugged drain) could fill the hose all the way back to the dishwasher.

Ken, the high loop doesn't help with anti-siphon---just give a hill the water would have to go over if the sink floods.

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 6 years ago

Angela, thanks

Warren, all we need are capes and x-ray vision now :)

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 6 years ago

I need a home air  vent has had water for the last 12 years! You just don't know what you don't know!

Posted by Shannon Coe, 916-597-3818, Lincoln, Rocklin, Loomis, Roseville (Keller Williams) over 6 years ago

Charles - I have never heard of these things - but we do not have disposals out here in the country with our septic systems.    Are they related to disposals?

Posted by Dagny Eason, Fairfield County CT, CDPE Homes For Sale and Condo (Dagny's Real Estate) over 6 years ago

Charles, love thinking of the 'water feature!' Thanks for the morning chuckle. Interesting to see how many parts of the country don't have air gaps; they're standard here in my area of California.

Posted by Lottie Kendall, Serving San Francisco and the Silicon Valley (Compass) over 6 years ago


I have never seen that water feature.  Now I have to make sure that the inspector checks this out.  Thanks.

Posted by Evelyn Kennedy, Alameda, Real Estate, Alameda, CA (Alain Pinel Realtors) over 6 years ago

Charles - Great Information - a Good Home Inspector is worth more than the buyers pay.  I always advise my buyers to have an inspection!

Posted by Carla Freund, Raleigh - Cary Triangle Real Estate 919-602-8489 (Keller Williams Preferred Realty) over 6 years ago

Charlie, That is a perfect example of why I think the air gap should be aimed at the sink. But as you said it is not required. Common sense says.....

Get em Mr. Squirty ; )

Posted by Donald Hester, NCW Home Inspections, LLC (NCW Home Inspections, LLC) over 6 years ago

I learned about the air gap device last year, Richard, when mine broke.  Thank goodness I was at home when it happened, because water started shooting out of it, flooding my kitchen.  It broke at the base, where the threads are, which I thought was odd.  I showed it to the representative at Ace hardware, and they had a replacement kit for it, so it must happen to other folks too.

Posted by Raymond Denton, Simple Man (Academy Mortgage Corporation) over 6 years ago

Shannon are you saying you have had a fountain for 12 years?  Too funny :)

Dagny, according to my friend Jim Quarello in Conn, you guys don't require them there.

Lottie, apparently pretty common all along the left side of the country

Eveyln, thanks for stopping by

Carla, an essential part of the home buying process for sure

Don, so many different requirements for so many different areas

Raymond I should think they most likely gave you a whole new unit---they are pretty inexpensive.

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 6 years ago

Another valuable lesson from AR community. Thank you for the information. Now, I just have to fix my connection.

Posted by Kimo Jarrett, Pro Lifestyle Solutions (WikiWiki Realty) over 6 years ago

This used to happen all the time in my old house.  Never knew it was an issue!  Oops.

Posted by Gene Riemenschneider, Turning Houses into Homes (Home Point Real Estate) over 6 years ago

We see the uphill plumbing come up in Flagstaff home inspections fairly often. It usually is a simple fix. Thanks!

Posted by Sylvie Stuart, Home Buying, Home Selling and Investment - Flagsta (Realty One Group Mountain Desert 928-600-2765) over 6 years ago

VERY VERY GOOD STUFF, that is on the home inspection reports here in Phoenix.

Thank you.

Posted by Jim Miner, Loan Modfication & Short Sale Specialist (Miner Noh & Associates) over 6 years ago

Kimo, thanks---let us know how it goes

Gene---whoops :)

Sylvie, thanks---yes, usually a pretty simple fix

Jim, Thanks

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 6 years ago

Once again I've leaned something new.  Thanks for making the time to share!

Posted by Dale Taylor, Realtor = Chicago Illinois Homes Townhomes Condos (Re/Max 10 New Lenox Illinois) over 6 years ago

Hi Charles,  That is soooo coool!  Do you know Bubba's number so I can get him to instal one for me? lol

Posted by Bob Miller, The Ocala Dream Team (Keller Williams Cornerstone Realty) over 6 years ago

Dale, you are welcome and thanks for taking the time to comment

Bob, don't we all have an Uncle Bubba?

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 6 years ago

Do you have a lot of those air gaps in your area?  I never see 'em... ever.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 6 years ago

Reuben in Seattle and the bigger municipalities---99% of the time and if they are not there it was because someone didn't know any better :)


Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 6 years ago

That's a bummer.  Those things are butt-ugly.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 6 years ago

That is why I like the Johnson-Tee  much better---no messing up the sink or countertop.

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 6 years ago