Maybe wise to check with a lawyer first but ….. can you turn off the water to that particular apartment?
Brilliant, Lady P. Absolutely brilliant! Except, on reflection, you might end up turning off water to the whole floor, or the building.
As for accessing the property without the owner’s permission, according to Section 122 of the Act, you can do so in an emergency. Not only that, if the owner has refused permission for you to enter (in an emergency) that have to pay for the door to replace the one you just opened with what firies call the “big red key” (a fire axe).
So what constitutes an emergency? Forget damage to property. What about the potential interference with electrical wires and making the whole building “live”. What about structural damage engdangering lives.
All you need is an email from a structural engineer or fire safety officer confirming that immediate action is required and off you go (but take a member of the local constabulary with you if you think there’s something nefarious going on in there).