I've just purchased a water butt, and need to find a way of getting the
rainwater from my house's roof flowing into it. One way, would be to fork
out £9 or so for a few ounces of plastic - i.e., a diverter.

Does anyone know of a cheaper but equally/more effective way? Is there a
way that doesn't require cutting all the way through one's downpipe?

I'm not even sure how effective those diverters are, anyway. What happens
when the butt is full up? Does the diverter keep sending rainwater to the
butt?

Thanks for any tips...

Al