On Tue, 04 Dec 2012 05:54:25 +0000, Hugh - in either England or Spain wrote:

On 04/12/2012 00:12, wrote:
Hi all,

Do modern WC systerns still need an external overflow pipe? I've been wondering for years why they don't just overflow down into the soil exit pipe and save boring extra holes through outside walls and whatnot. Now I have a Geberit wall frame unit to install and can't find any mention of overflow in the instructions, so I'm guessing maybe it doesn't need one due to this. Can anyone clarify the situation? I admit to being very out of date on this subject!

Thanks.

ISTR that there were regs about the visibility of overflows so problems
were not overlooked. It now seems that overflows that run down the pan
are accepted as being visible.
Neither of our WCs (one Topravit and one labelled Utopia) have external
oveflows.

My cistern overflows internally and down into the pan. A few weeks ago there
was a small leak around the outlet seal (or so I thought) and the only
indicators we
occasional burst of filling (could be a faulty inlet - it's a bit fancy)
dilution at the bottom of the pan
then, leaving the pan to dry for a couple of hours after flushing, the back
of the pan was still wet (the tissue test).

Replaced outlet seal - no go. Removed cistern and rebuilt the whole lot with
new doughnut and sealant - leak was worse! Tightened the assembly just by
turning it by hand (The bottom nut on the outside is very large and not very
thick, so tools don't work too well) and the leak stopped.

The point is, such a leak isn't visible and, in this case, might have been
10 - 20 li/week, so only just enough to notice and almost within expected
reading. Only the infrequent sound of the inlet was an obvious clue.

Better than a mate's warning pipes from the 2 cisterns in the loft:
went out to the gutter, then downpipe into ground, so no gully!
--
Peter.
The gods will stay away
whilst religions hold sway