Our lottie is at the end of a long run of council owned garages, 8 in total and the guttering runs along them to a downpipe on to the lottie, in bad weather we have our allotment drenched. I have installed 4 water butts in a row and they are allways full to the top, we water everything from these.
The garages have corrugated asbestos roofs, will the water be safe for watering?