The cupboard under the bathroom sink was wet (not flooded) and one of the valves was leaking slightly. The leak from the valve seemed sufficient to wet the cupboard floor but didn't seem enough to cause such a wet patch on the ceiling of the floor below (unless it's been dripping like that for weeks/months). The patch on the ceiling wasn't steadily growing over time. Last night it wasn't there, and this morning it was dripping through.
I shut of the valve to the bathroom sink and then the main valve. The dripping stopped a short while later.
Any advice on how I should proceed?
How can I identify if the leaky valve (or something else) was the cause?
Do I need to cut a hole in the living room ceiling so I can stick my head through and look around? Does the entire board that makes up that section of the ceiling need to be removed? Does the entire ceiling need to be replaced?
How do I assess this?