Bathroom Waste Pipe Route query

29 Jul 2010
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United Kingdom

I am moving a bathroom to the back of a back to back terrace and am struggling to interpret the building regs in relation to the maximum run for the waste pipes. The waste will need to travel 5-6m before being connected to the existing stack. 4 metres of this is travelling under the floor and out of the front wall and then 1-2m across the front of the building to the stack.

If I am reading the regs correctly this is OK for WC but not for bath and sink. Can I feed into the WC waste pipe first or will I need a macerator or some other solution? Any advice greatly appreciated.

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Thanks for the diagram.
I take it that the use of a durgo means my intended run is too long without it. Does a durgo usually finsih in the same room and if so do you normally just box it in a corner out of site?

Also the 3 units are all against a wall parallel to the external wall. To adapt your diagram to this scenario can I simply bring the bath waste from the left and the sink from the right to join the loo waste? Is there then any chance of the loo waste going back up into the bath?

(I'd draw a picture but can't find the option)
You could do it like this then
View media item 24615
There are various ways it can be done depending on the exact layout.

Max length of branch pipe is 6m and as you are near? that, a durgo is advisable (better). It can be sited anywhere within reason. Usually boxed in. It may need a vent on the boxing to ensure the valve operates correctly, it needs air, but as you have a vented (presumably) solum you could vent it from there inside the boxing.

"Is there then any chance of the loo waste going back up into the bath?"

Only if the line blocks.
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Cheers. My waste will actually need to go up per your revised diagram, given I can't take the smaller pipes diagonally through the floor joints is there any issue with bringing them in at right angles to the loo? I'll have a look what fittings are available tomorrow.

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