What he said.
Get that sorted before it fails in the middle of the night and makes you an unwanted indoor water feature.
In that context, under my kitchen sink (the one this thread's about is in the utility room) is a blue hose coming up form underneath with a tap on it - can I assume that's my rising main/main stopcock?
I mean, I know the obvious thing to do is turn it off and find out, but everything in this place is in such a state I don't want to touch anything unnecessarily till I get it sorted or looked at...