Dishwasher air-gaps are required devises in many states across the country and the best way to ensure you’re code compliant is to check with your local buildings department. Here in N.Y.C we have the option to use an air-gap or simply create a high loop in the dishwasher drain hose and secure it as high as possible under the sink base cabinet. I’ve been using the second option as described and honestly can say I’ve yet to see a counter top mounted air-gap in my everyday plumbing practice.
So what is the purpose of the dishwasher air-gap? It’s to prevent dirty contaminated sink drain water from backing into your dishwasher thus creating a potentially hazardous health issue. Not only is it unhealthy, but the stagnant water pooled at the bottom of dishwasher absolutely STINKS!. When I’m called in to address a leak under a sink, nine times out of ten I’ll find the dishwasher drain hose draped on the floor of the base cabinet and connected to either the garbage disposal or directly into a tailpiece.
What this does is allow drain water to migrate from the sink drain into the dishwasher and the homeowner has no clue it’s happening. They then open the dishwasher door and discover some nasty smelling water, especially if they don’t use the dishwasher that often. It’ll happen more frequently if the kitchen sink drain is partially clogged and draining slowly. The simple fix is to a. make sure the sink is draining properly and b. elevate the drain hose as high as possible and secure it to the underside of the counter top or cabinet wall. And if your state requires, the installation of a proper sink / counter mounted air-gap.
If a blockage takes place in the discharge hose between the air-gap and or tailpiece the sink mounted device will discharge water alerting you of a problem. You would be better served mounting it to the sink itself as opposed to a counter top, but each individual job will dictate what the best approach will be. If it does become clogged, you could remove the decorative cap and using the tube from a roll of paper towels attempt to blow free the blockage. On the other hand if it’s clogged with some hard food particles, you’re probably going to have to dismantle the waste hose under the sink to address the issue.
The point is dishwasher air-gaps are use to prevent hazardous sink water from getting into your dishwasher and contaminating dishes, utensils, etc. Check out the video below where I explain in detail why you need a dishwasher air-gap and an alternative option if your state does not require one. As always feel from to contact me at email@example.com, stay well and HAPPY PLUMBING!