Happy to share my mistakes as is well illustrated by the photo. I was caught by suprise, goodness knows why it was December, by a very cold spell. The water froze in the water butt and split it in several places; clearly irreparable.
Had I thought, and why I mention it now, is the easy garden tip to avoid the problem is to drain the water butt around now and leave it dormant until, say the beginning of March. Whilst we do have cold weather in March, in order to freeze the water it does require quite a severe drop in tempreture which is less likely in March.
If you need a constant water supply I suppose you could lag the water butt; although frankly there is usually so much water coming out of the sky why would more be needed?
Garden water Butt fractured by Ice
Gardening Tip Drain it now