I am fitting a new bathroom, and the sink and shower are next to each other on the internal wall (wall at the top of the stairs in an average 3 bed house). They will sit 93 inches away from the external wall housing the cast iron soil stack pipe (the wall directly opposite). I would like to run the basin waste down under the floorboards and have the shower waste tee into it. I then want the waste to tee into the bath waste and out into the stack. Is this possible? Are there any regulations on the size of piping I must use. I know there is adequate fall to cover this.

Thanks for that.

this si true ive seen a real popularity in 2" pipe recently, but for domestic its a bit overkill imo. Was actually thinking about mentioning that but decided against. Jerry is right tho 2" is another option,  if you are worried about the run it might be a bit too tight of a fit under the floor or whatever. The regs only say 1½" so go with that, 1¼" for basins.  Dont know how it stands in England but up here the basin is supposed to be run horizontally for the first 500mm from the trap( although with the increase in popularity in pedestal basins this is seldom actually done)

The following goes without saying of course, but I'll say it anyway.

Each of the connections (basin, shower, etc) should definitely have an S-bend or P-trap. You don't want a clean air feed between you and the stack under any circumstance. Some nasty smells in there which you don't want circulating.

Also, and again it's stating the obvious, make sure your loo isn't draining into the pipework at a higher point than the other shared resources. Having pee (or worse) coming up thru your bath plughole would not be a very enjoyable experience.

HM

http://www.odpm.gov.uk/stellent/groups/odpm_control/documents/contentservertempl...

there are good links on the regs forum for building regs that will help you out too, and dont forget, we are only a click away too

[quote author=HandyMac  link=1105443856/0#6 date=1105451852]Each of the connections (basin, shower, etc) should definitely have an S-bend or P-trap.
[/quote]
I've recently had to use some of these waterless traps, just a straight 'trap' but it has a rubber tube internally where the waste water flows.  The rubber is made so that it 'shuts' together when no water is passing through, thus forming a seal against sewer smells.



These are useful in bathrooms or cloakroom which are only used occasionally as the trap can't evaporate.  

[quote author=Ian_Reynolds  link=1105443856/0#13 date=1105526618]Blimey - it's like aladdins cave in here. That is exactly what I was looking for for my kitchen as my sink waste is bossed into the main stack and the local residents seem to hold a secret monthly 'throw a decaying carcus into the sewer' competition once a month, which consequently, despite a fully functional p trap under the sink, makes my kitchen stinks like a gents.
Is there any particular way in which that device needs to be fitted? [/quote]
Sounds like your trap is being sucked out, you could put an in-line trap in the run(although the trap Jerry describes looks like its in-line or maybe pedestal type) Lots of things can suck out a trap seal, wind blowing across the stack, discharge from other appliances etc.  I'd find the cause of the broken seal(and make sure its not the missus pouring fat/spaghetti etc down it!) Those strainer things for sinks are great to stop all that sh*t going down the plug, as it rots in the bottom of the trap it stinks!!!
Also, check your sink overflow for remnants of gunk as that can also cause a stink, so to speak.

ßtk

anti-vac traps are a good idea, should have mentioned them in my last post.