The Dishwasher Air Gap Story

This article appeared in our September, 2009 newsletter.  This brings us to the present.  Articles will be posted from now on as they are published in the newsletters.

This is going to be news to a number of people but that little chrome tower to the side of the kitchen faucet is not supposed to leak water into the sink.  Well, that's not totally right.  If everything is O.K. it is not supposed to do that.  If there is a problem it is supposed to do that.  Here is the story.

That little chrome tower mentioned above on your kitchen sink is the dishwasher "air gap."  If you have a dishwasher that drains into your sink drain system, an air gap is required to be there by code.  It is a safety device.  Typically the dishwasher pumps out the dirty wash and rinse water either into the garbage disposal or directly into the side of the sink drain tail piece (the pipe under the sink).  This is what happens in sinks where there is no garbage disposal.  If there were no air gap, some of the water in the garbage disposal or the drain could be sucked back into the dishwasher when the pump shuts off.  This could contaminate your clean dishes.  Also, if there was a bunch of stuff in the garbage disposal or the drain and it was enough to prevent the flow of waste water from the dishwasher, the pressure could damage the dishwasher pump and seals.  It would be a real mess.  So some bright person created these air gaps to prevent that from happening.

Please refer to Ken's primitive illustrations below to help visualize this.  They are pretty crude and not exact but they should help do the job.

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