The Brew Cabin

First, I am not an expert on drainage so please excuse me if I do not get the language correct. I am having drains laid for a ground floor toilet. I have dug the trench to the instructions given to me by the guy who is laying them. I have a two foot drop from floor level to the drain which then falls 3 inches over 16 foot to a new manhole. A rodding eye is to be fitted along this stretch. The flow from the manhole changes direction by 90 degrees and drops a further 3 inches over 22 foot to join up with my existing foul drain. Does all of this sound right, is there anything else I should be aware of. I would appreciate a bit of advice and assurance.

Cheers

(Edited by barrywalker at 11:24 am on Aug. 27, 2004)

3 inches over 16 feet (how I love these olde worlde measurements!) is equivalent to a fall of 1:64, which should be ok for a foul drain.

The 90º change of direction should be accomplished within the new manhole.

Then you have 3" of fall over 22 feets, which is a good bit slower, but @ 1:88 is just over the minimum recommended fall of 1:80.

If you were to combine the two runs into a flat bone, you'd have 6" of fall over 38 feets, which is actually 1 in 76m, just inside the min requirement.

Having said all this, I don't think you have much to worry about. The requirements of Part H of the Building Regs are 'on the safe side', and I think most BCOs would be happy to accept a relatively short run at 1:88 rather than require you to redesign the whole system to achieve 1:76.