What are these valves you speak of? I installed my dishwashers and the drain line just goes high before it goes to the disposal/drain. That is your backflow prevention...gravity.
There is always a bit of water sitting on the bottom of the dishwasher because of this. Of course my house is old with the original plumbing. they might add valves now.
There is always a bit of water sitting on the bottom of the dishwasher because of this. Of course my house is old with the original plumbing. they might add valves now.