I bought the air gap and cover to replace one that the builder had literally left under the sink. I have run the dishwasher 2x's and each time, water bubbles out of the air gap onto my counters.... The plumbers were out today to make sure that no lines were clogged: they weren't. They disconnected and reconnected the lines: tested it again....water all over the counters. There is a flaw in the design of the plastic air gap...have to go to a plumbing store to get a new plastic air gap... (The cover is fine..so far.)