I have a kitchen sink with a disposal fitted beneath. My dishwasher is hooked up to the left of the sink but it keeps leaking from beneath, soaking the floor from below. It has been fixed a couple of times. It is now leaking again. I suspect that the drainage plumbing is incorrect and that the dishwasher is also hooked up wrong. No less than four licensed plumbers have said that it looks fine, however, I can no longer believe them.

In looking up sites that offered dishwasher hookup instructions, it seems that we may be missing the air gap fitting and that the plumbing was not installed properly by the former owner of the house.

Please give me explicit instructions with illustrations so that I can fix the situation and then decide whether to fix this dishwasher once more or buy a new one. I do have a friend with the appropriate tools who can help me.

Thank you.