I think about this problem logically. I ask myself, what are the properties of water?
Apart from dripping into buckets I have strategically placed now in four locations under the plumbing. Apart from that. Water can travel a long way between the leak and the paddling pool on the cellar floor. And water conducts electricity!
Shark tuts at me and tells me that pure water does not do this; impurities conduct electricity, and that is why I should never plunge exposed wires into dirty washing up water.
But that would explain my ring main problem, would it not? If the rat chewed the cable, as rats are wont to do, then the plumbing dripped and travelled and the fuse blew on my ring main.
I am minded to take an evening course in electrical doodahs. I think I quite have the aptitude for this.