Relocating bath & basin waste to under floorboards

brightontraveller

usman330 wrote: »

Konark mentioned to fit the anti syphon. I think its because the bath waste and basin waste combine in to one waste pipe that goes to the soil pipe

Anti siphon traps cure some but not all problems hence the why ?
You may well find sink bath to the same pipe produces no problems at all so no need for anything as I mention the scenarios are all hypothetical

When you have two items in this case bath and sink connected to same pipe one or other discharging ( pulling plug out )may make a vaccum in pipe drawing water from other u bend etc Allowing smells from soil stack to enter (there are other things with traditional u bends etc) But in initial scenario either could cause this to happen so both would need it theoretically?

If I believe that to be the case I’d say for layman easiest to fit is a hepvo
See fig 10 on pdf page 14 it would explain better than I
http://www.wavin.co.uk/web/solutions/waste-water/waterless-traps/hepvo.htm#

then click "Product & Installation Guide - HepVO"

Or direct PDF link
Product & Installation Guide - HepVO

Or again two items connected when one discharges the water could flow back/up the pipe allowing water from discharges to enter other e.g. pull plug from sink a small amount water/air back flows to bath makes bath plug gargle or vice versa again theoretically ?
You could use non return valve on pipe
http://www.screwfix.com/p/mcalpine-t28m-nrv-40mm-non-return-valve-white/61561

or again hepvo there are other makers but this had pictures etc they are easiest to fit in confined spaces and generally easy to maintain replace etc