... being called down stairs urgently by SWMBO to find that the downstairs loo cistern had a large crack running from just around the side at the bottom and diagonally up across the front face, all the way to the top.
The crack starts small at the bottom/side and is a few mm wide at the top. It doesn't start at the spot where the fill pipe comes in, either.
Luckily the plumber has fitted an isolator valve as part of all the new work here so that and a quick flush quieted the deluge.
Anyone seen this sort of sudden catastrophic failure before? In a f***ing *loo* cistern??