Hey I've got an issue with drains and my kitchen. The kitchen is in the bottom of a double storey extension with a bathroom above it. I've attached a floorplan of the downstairs section. The red dots show the two drain locations. The left one is outside and is taking rain water from the guttering but the previous owners have also ran the waste from the kitchen sink and gas boiler (which is next to the sink) into it. The red dot on the right, next to the down stairs toilet is the soil stack that has a connection to the bathroom waste on the floor above, the stack runs through the ceiling of the utility room (utility room is single storey) and into a separate drain. The kitchen has been completely stripped out and I'm about to refit it but I'm concerned about the sink and boiler waste running to the wrong drain, especially as I intend to add a dishwasher next to the sink which will have food waste in it as well as waste water. The problem I have is that I don't see any easy way of tapping into the soil stack as the waste from the sink and boiler (and dishwasher in future) would have to cross that doorway at low level. The floors are concrete but even if they weren't, I don't think it'd be an easy task to join into that soil stack and not much of a slope on the pipe. Any suggestions? Thanks!