Soil Pipe Angle

daveygravey · Mar 29, 2011

Hello,

I am relocating a toilet in an upstairs bathroom and while I am at it I am replacing a cast iron soil pipe that runs the the height of the house venting just above roof height. The toilet waster outlet will be approximately 1.5-2 metres from the soil pipe.

My question is in regards to the soil pipe and if I can connect the toilet waste horizontally using a 90degree branch fitting.
http://www.screwfix.co.uk/prods/29610/Plumbing/Soil-Vent/92-5-87-5-Branch-Black-SP190

Therefore the toilet waste will come out of the toilet do a 90 degree bend horizontally and then the waste will flow horizontally into the branch in to the main soil pipe and away.

Is this acceptable or do I need an angle on the flow out of the main toilet?

Thanks,
Dave

dontknowitall · Mar 29, 2011

You will need a small slope but you'll also find the fittings are actually 92.5 degrees instead of 90 degrees so this will give some of that angle you need. Anymore than around 2m and you might have difficulties but as long as you can get some sort of slope on the soil pipe you should be fine. I think the official drop is meant to be 18mm per metre but I'm not sure.

fagsanbooz · Mar 29, 2011

as long as all horizontal pipework has fall on it 18mm+ per metre, then should be ok

daveygravey · Mar 31, 2011

fagsanbooz said:
as long as all horizontal pipework has fall on it 18mm+ per metre, then should be ok

18mm does not seem that much over a metre, will it be enough for the richards to flow?

dontknowitall · Mar 31, 2011

daveygravey said:
18mm does not seem that much over a metre, will it be enough for the richards to flow?

Yes - you don't want it too steep because solids can then flow too fast into elbows and stick there while the water flows past. Then more solids can stick and you end up with a blockage.