I decided that the tap was going to leak again sooner or later and that water is too precious to lose, so I installed the outside tap inside the greenhouse for now. It is much harder to leave on by mistake. We put a little water into the tanks to check the leak isn't somewhere else and then turned the unrotted stuff from one compost bin onto the newly emptied one.
We saw our neighbours from across the street who are helping out with a plot that someone else can't manage for the moment. I hope they get as much from their plot as we do from ours.