"pp" wrote in message
o.uk...
Hi

I wish to fit a water butt to collect rainwater from the roof but I have
noticed that the bath and basin water from the bathroom discharge into a
hopper that splits the downpipe from the roof. Consequently, the water
butt will fill not only with rainwater from the roof but also bath and
basin water from the bathroom. Surely this is not right? Would I be right
in thinking that this is an illegal setup? I must mention that the toilet
does not discharge into this pipe!
Any advice would be helpful please.

Perhaps its time for some new guttering and separate down pipes where you
could tap directly into the rainwater down pipe. Purpose made tap off
adaptors are available. (I'm not following this suggestion as I'm retaining
my cast iron gutters and pipes) Many water authorities offer a reduction
on water rates if the roof water runs to a soak away rather than discharged
into the drains.

Housing developments built after the war tend to have separate surface and
foul water drain systems. New towns built after the war have completely
separate drainage systems, but most older towns have mixed arrangements,
with separate systems in the newer parts and combined in the prewar areas.

The advantage of the separate foul and surface sewers is that the rainfall
water is discharged locally into a river or lake maintaining the natural
flows and ground water levels. Also a summer storm is less likely to
overload the foul system causing unpleasent flooding. The down side is
that some people consider a street drain as a suitable place to dispose of
their old engine oil/paint/thinners/creosote/garden pesticdes etc and this
then emerges in the local water course.

Combined foul and surface drainage sewers usually have some kind of storm
flood arrangement, for example an underground weir discharging any excess
directly into the sea or river, the high flows at that time minimising any
pollution problems.

Roger R