I am installing a dishwasher and garbage disposal in a kitchen where there were none before. Standard instructions say to create a high loop with dishwasher drain hose and connect it to the dishwasher drain port on the disposal (after removing knock out). A plumber I spoke to said to bi-pass the disposal port an attach the dishwasher drain hose behind (downstream of) the disposer to avoid noise and potential clogs. I've heard that if a disposer is present, you must by code, attach DW drain to it. Is this true? Is there a good reason to drain the DW into the disposal, or can I by-pass the disposer input with no issues?
Additionally, the disposer drain fitting is a pvc elbow which requires a loop or small "trap" be created before horizontally teeing into the vertical drain in front of the main trap. I was told I can remove this elbow and go straight to the tee. Is this true?