Bathroom waste pipe routing

[smqa]

I'm fitting a bathroom and would like to hide as much waste pipe as possible. I would like to run sections of waste pipe that retain water (like a long u bend) in order to have some of the run under the floor.

reason for question is the bathroom is an internal room (no external walls and soil down pipe is in an adjacent en-suite (also an inetrnal room with no external walls)

I'm quite happy to box it in above floor level if this is the only sollution but want to know what the implications of the above are.

i can provide more detail if the question is too vague.

thanks

 

[hi-spec plumbing heating]

more info will help.

 

[smqa]

more info

waste is center of 1.7 x .7 bath. After bath trap I want to run waste along length of bath above joist level (but under bath). At bath end panel i want to drop waste pipe below floor level, run under the floor for 0.4m to then come back above floor (inside gebrit wall hung toilet fame) and continue fall to main soil stack( all boxed-in in the adjacent en-suite).

the 0.4m section under the floor will be retaining water (like another u bend) and i'm unsure of the impact on bath draining. All pipework will be below level of the bath so physics means it will drain past first u bend, i just want to be sure that i'm not contavening building regs etc.

thanks

 

[hi-spec plumbing heating]

not practicle to have the waste come back up.
you must have the waste going down hill all the time at min of 18mm/m
and no waste pipe is to hold waste water
it will also cause no end of problems with flow.

 

[smqa]

thanks for advice,

i'll box it in

 

[Space cat]

You'll get an airlock between the real trap and the one formed by your loop under the floor. In order to force water out of that loop at its far end, the water in the bath will have to be higher than the trap outlet by an amount equal to the vertical rise at the end of the loop. I would guess that this will be above the plug hole. Your bath won't drain.

I might add that a builder once landed us with a very similar airlock problem. He took the drain from a washing machine (with trap) out through a wall and into an old drain gully. That would have been alright (all our waste goes into the same sewer) but then he sealed the pipe into the gully with a plastic bag and concreted over the lot!