Plumbing a bathroom sink waste into the bath waste

[BERT_UK]

Hi all - i'd appreciate any help on this as I can't seem to find any good advice on the Net and these forums seem very helpful! Also i'm a fairly basic plumber (but will be getting assistance)

I am planning on installing a new bathroom suite. At present I have low level pan toilet but would like to replace this with a new close coupled pan to modernise the room. Unfortunately the sink waste currently runs at the height of where the cistern for the close coupled pan would need to be. The bath waste is lower and would run under the cistern.

Therefore can I plumb the sink waste into the bath waste pipe without any problems? I'm thinking that when the bath water is drained this will push air up into the sink and make the water in the sink's U-bend gurgle and even enter the sink? Are there valves\connectors\etc to stop this?

I'm guessing the current bath waste pipe is also on a slight angle (I can't find my spirtit level) to drain to the soil pipe and so the sink water couldn't run towards the bath.

Many thanks for any help. I hope what I am trying to do makes sense?!

 

[Paul Barker]

Get a 1 1/2" swept T orientated so sweeping points outside, get a fitting which fits into an 1 1/2" fitting and is an 1 1/4" fitting itself, that's where you join you basin waste. You shouldn't have any problems if it goes into a hopper and a gulley or is bossed after adrop into a soil stack outside with a vent pipe. It's when people don't vent their soil pipes you lose the integrity of the water seal in the traps. You can supplement the trap with a hepvo fitting but it's not necessary.