sm_jamieson wrote:
Just had a moment of drama. The main roof gutters of me and neighbour
had a shared downpipe that I guess was supposed to split equally
between the 2 properties. I had temporarily routed both roofs onto
neighbours side whilst extension work is in progress (a bit naughty I
guess). Anyway, just had downpour, and she phones saying it overflowed
and flooded her back door.
Now, we have combined sewer and drains here (1930s house).
I have temporarily re-jigged it so that all water goes to our side,
and down our soil pipe, which currently only extends 2 feet above
first floor, awaiting the extension roof. This will certainly keep her
happy.
But it got me wondering. For a combined sewer, why not just put the
roof drainage into the top of the soil pipe, which passes right by the
gutter ? I mean, a 4 inch pipe from the roof must be the best
solution. Even in heavy rain, there would never be enough water from
the roof to prevent venting when the toilet is flushed.
??
Simon.

Because the top (IE the open end of the soil pipe) has to be a minimum of
one metre higher than the highest opening window, and in your scenario, it
would be gutter height.
This is why soil pipes have the swan neck to take them past the eaves and
gutter and upwards for a stretch before venting.

--
Phil L
RSRL Tipster Of The Year 2008