all waste down one pipe?

[Lotarogg]

Hi, have got to the bathroom stage of my renovation now and trying to work out the piping. Can I run a waste pipe from the toilet and connect bath, sink and shower all to this outgoing pipe, or are there any regs that say they have to be separate?

Cheers

 

[TicklyT]

You will probably find the waste outlet from a bath or shower tray will be lower than the soil pipe from the WC, and water doesn't run up hill.

The basin waste is usually above the level of the soil pipe, unless you have a very strange bathroom.

You could consider teeing the bath and shower waste together, and running that to join the stack lower down. Many recommend increasing the pipe size to 50mm after the tee. If the pipe run is long, you should do that anyway.

Design in adequate rodding points to deal with any future blockages - if you do, you won't need them, if you don't, you will!

 

[Richard C]

Teeing waste connections always runs the risk of siphoning the traps & back filling. Best practice is to have separate stack connections for each appliance but if it’s impractical you will probably need to either vent the waste runs or fit anti-siphon traps to prevent gurgling noises & smells; you may also need to increase pipe sizes. There are regulations that govern size & maximum length of unvented waste runs, stack connections & provision for cleraring blockages, see here;
http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADH_2002.pdf
Other regulations also apply with regard to ventilation, electrics & even sound insulation if you have new timber stud walls.