DIY Doctor UK DIY Forums

I am installing a new kitchen in a room with no services, including drainage. The drainage is required for a sink and adjacent dishwasher. Unfortunately the kitchen installer I have employed does not seem to know about this part of the job, so I am trying to work it out. The floor will be tiled, so everything below it has to be right.
I am thinking that the dishwasher drain will attach to the sink trap and a 40mm pipe drop straight down through the floor into the void below the floorboards, solvent fixed to a 120 degree bend and 40mm pipe out though the wall at the lowest point just above the concrete plate. Once outside the 40mm pipe will join a socketed square hopper. The hopper will be joined to a 'p' trap gully via a piece of 110mm pipe with a socket or double socket. The 110mm outflow from the 'p' trap will run about 4 meters to join an existing 110mm drainage pipe via a 'y' 45 degree junction. I want to use a three socket one but not sure if it is possible to fit one of these effectively into an existing fixed pipe run? Perhaps I need to lose one of the sockets and use a rubber sleeve with jubilee clips to join?
Any comments on this or the general drainage plan much appreciated.

Hi rhino666,
You’ll probably need to use a 90 bend in place of the 120.
It’s probably worth fitting a mini inspection chamber with sliding collars for the final connection.
Regards S

Thank you stoneyboy, appreciate your reply.
Yes, agreed a 92.5 degree bend will facilitate flow as well as accommodate solvent fixing to the hopper.
Now here is my remaining dilemma, considering the tiled floor going down, which once down I NEVER want to touch again. Do I go through the floor and out of the house direct to the hopper with all waste pipe hidden but if a problem, will be a real issue............or do I chicken out, as most seem to and go out of the house above the floor level, with an unsightly pipe dropping on to the hopper grid?

Hi rihno666,
Do the underfloor option using a continuous length of pipe - support it at regular intervals.
If it creates problems in the future you could bypass it with the exposed pipe option.
Regards S