Christian McArdle wrote:
If it is just a plan then a vertical rise at the end certainly
does not comply with the Saniflo instructions and thus would
undoubtedly invalidate the warranty.

Indeed. The Sanisplit, on the other hand doesn't have this restriction,
which is why I would recommend it if this pipe routing was chosen.

Of course with a Saniflo it might well be easier and better to go up
from the first floor cupboard and through the loft (assuming a two
storey house) to the stack. This would avoid a lot of difficult work
under the floor and could all be done in 22mm pipe, assuming the
length is suitable.

Yes, that would probably be a preferable routing if feasible.

Christian.

Thanks to all.

The length of the drain pipe from washing machine under the floor is
about 15 foot, 5 metres. At a 1 in 40 fall (that is falling 1 cm for
every 40 cm in length) that is a pipe fall of about 10cm. That will
just be enough space in the floor. I can take the pipe out of the
outside wall which opens up into the roof space of the brick lean-to
kitchen. From this space I can then take the pipe outside via the side
of the lean-to and down into a gully below.

I can take the drain pipe across the floor, rise and connect onto the
toilet 110mm elbow. It could rise 3 foot so no soil from the toilet can
run into the washing machine drain. The Sanisplit pump should be
capable of doing this. Can I tee into the soil stack just behind the
toilet? I see no reason why not as long as the pipe rises above the WC
pan preventing backflow.

If this is not feasible because of obstructions, the Sanilav, which
uses 22mm pipe can rise up and across the loft and connect onto the
stack outside. It may be tricky getting the 22mm pipe out of the eves.
Does it have to be copper pipe? Sanilav have a model that is about
£210 for basins and showers. Would this do a washing machine and
condensing dryer? I can't see why not. I "think" it has a 22mm
discharge pipe.