Drains: Maximum length of underground 110mm soil pipe?

[JFD]

Hi, Can anyone tell me if there is a permissible limit to the length of an underground 110mm soil pipe (before it meets the main, public, large-bore pipe running under the road/street?)

Thank you..

JFD

[Tim+]

I suppose it depends on whether there is a "standard depth" for street sewers. The attainable slope on your soil pipe will determine its maximum length (I guess). Not an expert though...

Tim

[Andrew]

If only your property is using this pipe then provided you have access points at every bend and the fall is correct over the entire length, then the only limit is how deep the public sewers are.

The estate where I live uses 110 mm to interconnect blocks of terraced house but despite the gentle slope, the run they take before joining the 150 mm stuff is like a dogs back leg.

To much fall is as bad as not enough.

[John Rumm]

Approved document H is the one you need. Available here:

[JFD]

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Thanks for the replies. I can't find anything in the Building Regs Part H r egarding maximum length. This surprises me, because when you flush a loo, t hat gallon or so of flush water has got to carry the human waste along, and the longer the run, the more of that water will be used up moistening the inside of the soil pipe. So if, say, you had a run of 1/4 of a mile, I woul d imagine that nothing would reach the other end, even with the correct gra dient. In my case, the entire length would be about 35 mtrs, and with the correct gradient.

JFD

[John Rumm]

The limitation is that of depth. You have a minimum and maximum rate of fall, that in turn implies your length is constrained by the height available for that fall.

[Vir Campestris]

Way back in the 1970s my parents built a house 120 metres back from the road. The drain worked fine, even though the slope was right on the shallow end of what was permitted.

Andy