Sometimes I truly think that people do things in their home with the sole purpose of seeing how hard they can make the inspector laugh.
The following plumbing problem I came across on a recent inspection might make anyone familiar with the installation of dishwasher air gap devices howl out loud. The rest of you will have to laugh vicariously.
The dishwasher air gap device prevents dirty water from being drawn back into the dishwasher should the sink and drain flood.
Being a sanitary apparatus, keeping effluent out of the dishwasher probably sounds like a good idea.
You will find arguments to support the idea that an air gap device is not really necessary as long as the drain makes a “high loop” to the underside of the countertop. This discrepancy arises because some jurisdictions follow the IPC (International Plumbing Code) which allows the high loop, while other jurisdictions follow the UPC (Uniform Plumbing Code) which says there has to be an “air-gap.”
In my humble opinion it is “best practice” to have an air gap regardless of what the code says. If the sink and drain were to truly flood to the rim of the sink and onto the kitchen floor, the level of water is necessarily going to be above any high loop under the countertop---end of story.
People’s sense of aesthetics sometimes gets all riled because they don’t like the “look” of the air gap device protruding through their nice granite countertop or sitting on the sink. If it is an under-mount sink there might not even be a place on the sink to mount the thing.
Enter: The Johnson Tee. The Johnson Tee is another way to create an air gap without having the abysmally ugly chrome trailer hitch mounted on the not-to-be-adulterated countertop.
This apparatus is hidden in the wall and will have a decorative cap that vents to the outside---or sometimes to the back splash---although to the outdoors is typically preferred when possible. Here are a couple of pictures that show what the rough-in of the Johnson Tee assembly looks like with its cap on the exterior. Pretty cool don’t you think?
This clearly gets the air gap above the flood rim of the sink and off the countertop.
The other day I found the most unusual installation of a Johnson Tee that I have ever seen---I am still laughing out loud to myself!
Let’s ask some questions about this installation.
Is it above the flood rim of the sink?
Will it function to keep dirty water out of the dishwasher if the drain backs up?
Will a backed up drain come out of the air gap device and flood the cabinet?
Will sewer gases come out of the air-gap device because there is no trap in the drain to prevent it?
Like I said, am I on Candid Camera?
Charles Buell, Real Estate Inspections in Seattle
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WA State, Home Inspector Advisory Licensing Board