There's a simpler answer that works for the Iowa HD. Get a plastic tub and mark it "Veggie Wash Only". You can fill that with water out of your triple sink, rinse off your produce, and pour the water down the wash basin when finished. Much simpler than messing with the plumbing.
Brian Sweeney - CBJ #3691 - '77 Step Van Mobile Kitchen, Horizon Marshall, WSM with Pro Q Stacker, Weber Kettle & Smokey Joe GOLD.
"Any sufficiently advanced technology is indistinguishable from magic" - Clarke's Third Law