40mm waste pipe underground

[P.J.]

Hi All,

I need to run some 40mm waste pipe from a sink/washing machine out the wall and then about a foot underground for 3m to the gulley (to pass some french doors). Is that OK practice and do I need to bed it in something in particular like sand ? (I can get the required rate of fall to the gulley).

Cheers !

P.J.

 

[kevplumb]

if your going to bury it sand aint a bad idea
make sure you fit a rodding acess point(s) in case of blockages

 

[brown-nought]

At 40mm you are limited to a maximum unvented branch pipe of 3m. This is measured from the furthest trap.

 

[kevplumb]

good point bn use an antisyphon trap

 

[htgeng]

good point bn use an antisyphon trap

buried under the floor?

 

[brumylad]

If its not going to be buried very deep my concern would be that it will get damaged and leak. If it does your house will get damp.

A better solution would be to dig up the drains and run a new gully and straight run of drain to join the old one at a new or existing man hole.

GO ON hire that mini digger.

 

[ChrisR]

"Pea Gravel" is what's usually used for drain underground. Use the best quakity stuff like Terrain, and I'd go up a size to 2". Less likely to give any bother and easier to clear if it does.

 

[P.J.]

Thanks for all the advice.

My waste goes: Sink, 2.5M of waste pipe, washing machine trap, out the wall and under ground, 3m of waste pipe, tap into rainwater drain.

I'll bed the pipe in well and if I get a gurgle at the sink, I'll fit an anti-syphon trap after.

Thanks for all your help.

P.J.