bath and basin waste ? All aspects of plumbing questions and answers, help, tips and information

[tony636]

hello, i'm going to be changing the waste pipes in my bathroom, the basin is running at 32 mm and the bath is running at 40 mm. thats not he problem, they both enter the soil sack, bath waste is lower, then the basin waste comes in about 350 mm higher up. Can i use 40 mm for the bath and as it runs past the basin, drop the basin waste into the same pipe using 1 pipe for both flows? please help. :?

[chris_on_tour2002]

i see no problem with running the 32mm into the 40mm. if it were the other way around, ie 40mm down to 32mm then it may be a problem as it may cause your bath water may drain very slowly.

[Steve the gas]

I have so yes, it works fine.

[plumbbob]

Sorry to disagree with everyone else, but although sometimes you have to combine wastes, it is not good practice to do so. Two problems occur. Firstly, when the plug is pulled in a full basin, water will often flow up the bath waste and cause a gurgle in the trap. sometimes water can actually flow up into the bath. Secondly, when the basin empties, and the water drains away, it can pull all the water out of the bath trap breaking the seal and allowing odours up into the room.

[bobbych]

its fine to do as yu say but 1 consideration is if the bath drains fast it may try to pull the water seal from the basin trap. It may gurgle. If it does you can fit an anti vac trap to the basin

[tony636]

:D thank you to the guys that have sent me replies to my question .