"Roger Mills" wrote in message
...
A lot of cisterns don't have external overflows these days but overflow
into the pan. Bad idea if you're on a water meter because you're less
likely to notice that it's overflowing.

If they do it now (ie it's not contravening some safety regulation) I wonder
why toilet cisterns were *ever* made with external overflows, given that the
overflow pipe could always be connected by T piece into the outlet pipe of
the cistern to the pan - even in the days before flush-fit cistern/pan
connections.

I agree, though, that it makes it almost impossible to tell when the cistern
is overflowing and therefore that the ball valve needs some attention.