Hi,

I have just been trying to install a waste for a new dishwasher. The
waste, already there for the washing machine (long before my time) is
a 40mm pipe running at a slight down angle along the back wall, where
it passes the sink and eventually joins the main waste pipe. The
machine hoses drop into the slanting pipe along its length.

I've noticed that the waste currently used by the washing machine, and
which I was also making use of for the dishwasher, is untrapped. My
sink has a spigot trap, but I'd rather not use that as it makes
removing the units tricky. Is there any reason I can't simply remove
the spigot trap section and connect the slanting waste to a T joint
just above the sink trap? If I can't, I'll just have to put a separate
trap on the machine section of pipe...

Cheers,

Ben