Set Square wrote:
In an earlier contribution to this discussion,
Dr Wu wrote:


Is trap essential for dishwasher ??


It depends on where the waste pipe goes. If it goes into a stack, yes.

Mine goes out through the wall, and into a gulley - so the gulley acts as a
trap and there's no need for one inside.

But that implies if your kitchen sink empties into a gulley, then
similarly you wouldn't need a trap under the sink. Surely not so??

David