Will my rainwater be safe?
Nigel Clarke, Chesterfield, Derbyshire
Stefan says: After our hot and dry summer, your thoughts have turned to saving as much rainwater as possible and you wish to collect it in water butts. You feel the rainwater draining from your tiled house roof will be fine but you also have a garage with a corrugated, non-asbestos fibre cement roof and wonder if rainwater collected from there would be safe to use on young tender plants, or would it contain contaminants from the sheeting.
I’m no materials chemist but my feeling, judging from your picture, is that the sheet is well weathered as it has moss and lichen growth. I’d be surprised, therefore, if it contained anything harmful. Also, the water drains quickly, so hardly has time to absorb anything. That said, I never use stored rainwater from butts or barrels on tiny seedlings.