Is my plumbing layout okay? Please help

[tomcox]

Hello, I am fitting a new bathroom, and changing the layout. I've fitted one bathroom before, but I did have issues with smells occasionally, that makes me think I might be fitting the waste system wrong.

Does anyone with experience know, does the below look okay?

I've read on some places that every trap needs a vent? or otherwise I might need anti-syphon traps or AAVs?

Any help would be appreciated!

 

[fowlerboi]

The issue you have is the bath which is a big body of water siphoning the trap on the basin. While it might work fine on completion when the pipes are nice and clean, once they get fill with crap the water can't get away quickly enough and creates a plug which siphons the basin.

To get over this take your basin waste back to the soil pipe without teeing into the bath. Or tee into 50mm waste pipe where the bath or basin meet. Or put on an anti-vac basin trap/ Both 50mm waste pipe and the anti vac trap. The first option is the best.

There is no gain from running the basin waste pipe all the way to the other end of the bath to tee in.

 

[plumbingservices]

The issue you have is the bath which is a big body of water siphoning the trap on the basin. While it might work fine on completion when the pipes are nice and clean, once they get fill with crap the water can't get away quickly enough and creates a plug which siphons the basin.

To get over this take your basin waste back to the soil pipe without teeing into the bath. Or tee into 50mm waste pipe where the bath or basin meet. Or put on an anti-vac basin trap/ Both 50mm waste pipe and the anti vac trap. The first option is the best.

There is no gain from running the basin waste pipe all the way to the other end of the bath to tee in.

Completely agreed! I think the best way is to take the basin pipe to the soil pipe without teeing into the bath.

 

[tomcox]

The issue you have is the bath which is a big body of water siphoning the trap on the basin. While it might work fine on completion when the pipes are nice and clean, once they get fill with crap the water can't get away quickly enough and creates a plug which siphons the basin.

To get over this take your basin waste back to the soil pipe without teeing into the bath. Or tee into 50mm waste pipe where the bath or basin meet. Or put on an anti-vac basin trap/ Both 50mm waste pipe and the anti vac trap. The first option is the best.

There is no gain from running the basin waste pipe all the way to the other end of the bath to tee in.

Thanks guys

I did think about a separate tee into the soil - issue is, in that area on the soil stack, there's a manifold, then above that there's the tee where the toilet connects. The lowest place I could make a new tee is really high off the ground, and I wouldn't be able to run that high and still get under/around the bath.

I will definitely do the 50mm pipe option though, and maybe just get an anti syphon trap for the basin as well.

Thanks again for the help - appreciate it