Fitting a plastic soil pipe branch

11 Jan 2006
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United Kingdom
I hope that this is in the correct section ie 'Plumbing' rather than 'Building'

I am going to replace my old cast iron soil pipe with 110mm dia. plastic. Its a fairly typical installation with a branch connection at 1st floor level to take 1No. WC connection and nothing else. The branch has a 92.5 degree connection for the short length of pipe from the WC. The branch I have is shown here and the bend coming off the WC and out of the wall is shown here

Am I right in thinking that the short length of pipe between the branch and the bend should be installed at the same angle as the connection into the branch ie 2.5 degrees to the horizontal. The reason I ask is that the same section of existing cast iron pipe, probably falls at about 10 to 15 degrees. 2.5 degrees does not really seem adequate to me to allow the waste from the WC to discharge properly into the stack :rolleyes:

I would appreciate any advice.

Mr M
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2.5 degrees or 1 in 40 is considered adequate.
Too much drop is considered bad practise. Water can run away too quickly, and leave the solids behind.
Thanks TicklyT. I never thought of it from that perspective.

Mr M

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