I've had this house a little less than a year. We've had issues with nasty water turning up in our dishwasher. We assumed there was just something wrong with the dishwasher/filter, etc…
Upon inspection of the drain setup, the dishwasher is plumbed in directly to the top of the garbage disposal. We discovered water from the sink was making it's way right into the dishwasher.
It seems, that there is supposed to be an "air gap" fitting installed, that I assume is what would prevent this from happening. There appears to be no such animal in this install, and the port from the GD is plumbed directly to the dish washer.
Is an air gap setup all I need to resolve this? I was debating on skipping the garbage disposal and plumbing directly to the drain pipes, as it would be a lower point in the system, and less likely to cause drain back to the dishwasher.
Best Answer
having just redone the dishwasher, sink, disposal and faucet/drains in my kitchen I can hopefully help you here. You shouldn't need an airgap for one. I actually removed mine when I redid them because I found it to be ugly and both the dishwasher and disposal manuals say one was not necessary. What you can do is loop the dishwasher drain hose so it reaches above the connection to the disposal, this should keep stuff from running backwards into the dishwasher. I am however concerned that this is happening in the first place and might suggest checking your disposal to see if it is clogged or having other drainage issues as the water level in the disposal shouldn't ever get high enough for water to backwash down the to the dishwasher.
Also running the dishwasher into the disposal is beneficial so any large food waste goes through the disposal instead of directly down your drain so I wouldn't change that part out.
I would also double check your manual for your dishwasher to see if it has special instructions for the connection without the airgap.