Waste pipe from toilet to stack.... horizontal?

[henryfire]

Good afternoon, putting a new bathroom in and just wondered if someone on here who knows a bit can help me out:

I'm installing a new toilet and wondered if waste pipe from toilet should be exactly horizontal or should it have a slight fall on it towards the stack? Normal wall its going through, Brick-cavity-block.

Many thanks

 

[hi-spec plumbing heating]

18mm/m min drop.

 

[henryfire]

thanks for lightning reply, 18mm per meter, the run to stack will be about 500mm, so tiny fall is required?? 9mm?

 

[hi-spec plumbing heating]

in that short distance if it's going straight out the wall in to the soil stack not a problem as the flush will push it that distance . it's when you have a run you can get probs and need a good drop.

 

[henryfire]

cheers