Hello there, after months of on and off searching for solutions, I think I have found the solution to my 18' Dishwasher Drain install. The DW placement is at the end of a 14' cabinet run and then the line turns/curves 45 degrees about another 4' to the sink. Most places said, "No you cannot install it that far." And some said, "You can install anywhere as long as you place the high loop or air gap close the the DW and then let gravity take care of the rest." (Thanks speedball1!)

I also saw the suggestion to use a continuous piece of PEX. I assume that would reduce the chance of build up and therefore clogs. Does anyone have any other suggestions or is the PEX one of the best ways to go?

I also had the idea to have another high gap next to the disposal. Would that be unnecessary, detrimental or a stroke of genious?

One last small question, how flexible is the pex for my 45 degree turn?

I suggest you omit Air Gap. Run loop immediately at the DW and then slope discharge towards the GD at 1/4" per foot. Since discharge from DW is pushed by pump you should not have problem with drainage. If you use rubber hose for discharge, make sure there are no kinks and hose is not flattened where you are making the 45 degree turn. Attach the hose with clamps to the back of the cabinets to assure the slope won't change. Also, for the long run, you could use rigid PVC pipe.

Or, you can extend solid ABS / PVC drain from the sink, through the cabinet, all the way to the DW. Then, connect as usual.

Back to you. Milo

I agree with Milo, Lose the GD loop and let gravity drain the pex.
A second loop would trap the line. Just make sure the drain line's secured with pipe straps. Good luck, Tom