Waste pipe gradients

There is a design curve for 32mm pipes tacked on the bottom of Diagram

I always use the addage 1" in every metre length, it's always worked for me.

Indeed - anything from 1 to 4" per meter is usually fine (and just about fits in with the approved doc anyway!)

Wouldn't 1" per yard be more sensible? ;-)

John Rumm coughed up some electrons that declared:

Ah got it.

Thanks John.

I've got a 5m run[1], so looks like I might have to upgrade that to 50mm pipe for better effect. Doesn't meet regs, but I'm not bothered for this - just means the bath won't drain so fast.

This takes it to a remote stack branch that's grey water only. I could dump it in with the local loo stack, but I don't think I can get the boss low enough for a bath drain - and it makes me a bit suspicious as any problems on that pipe and the bog might back up the bath (yuk). Rather a slow bath than a brown one!

Anyway - might just manage a 1:60 fall which is close enough to the 1:55 quoted. The kitchen is much easier - I've got quite a choice of gradients as sink drains are higher - so I was mostly looking for design figures on that.

Cheers

Tim

Ray coughed up some electrons that declared:

That's a good reckoner - I'll think I'll work to that for the kitchen.

Ta

Tim

I haven't read the approved Doc so apologies for ignorance. As a newly married DIY sprog back in the late 1960's ISTR some regulation regarding the length of waste run allowed before some means of air admittance was required. U bends were common then so this may not be relevant to P traps.

regards

On soil connections, the current rule is something like the new connection should be no more than 6m from a ventilation point. Otherwise you need to add a vent stack or a AAV.