If one finds a split in a standard modern plastic water butt, as typically
found at B&Q and every garden centre, what is the best way to repair it? I
suspect the plastic is polypropelene, but I may be wrong. I wondered about
using a hot soldering iron to melt the plastc together, over the split, or
would it be better to use that black mastic gutter sealant stuff sold in
tubes for mastic-gun application? Which would make the strongest most
durable repair?

TIA,

Al