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.

Phil