Posted: 04/11/2012 at 13:15
I've had 3 of these wonderful Belfast type sinks in the garden for many years - though not full of water, but full of sometimes very wet compost. They have been frozen solid time after time, and have not yet come to any harm. If you remain worried, wrap it in some horticultural fleece (not bubblewrap as it can trap the water against the glaze, which can chip off if then frozen), or sacking, or old curtains or whatever is availble. They are very tough things though, as are water lilies, which freeze solid too quite often and seem to thrive on it.