Mum would like to do her bit to lessen the drought in England so she's commissioned me to connect a water butt to our drain pipe to collect water. The problem is that the bathroom sink (and I suppose the bath) also connect to the same drain pipe. All manner of detergents and other herbicidal products are liable to make their way down the sink or bath drains so I don't want to collect this water. I can think of a number of possible solutions but not necessarily the smartest. What would you suggest?