George this looks like an issue you should take up with U/L or the other listing agency. It is clear the writer of those instructions never saw plastic water pipe. As an inspector I would want to see it bonded to the EGC of the circuit feeding it. As an installer I would bond it to the PVC pipe with weedeater line and a tywrap for a clamp. (after I made the EGC connection in a proper manner) Inspectors need a laugh too.
