I decided to change my upstairs bath taps so I turned off the cold water at the mains and drained the hot water tank, After replacing the cold tap and not fitting the hot tap, I then made the mistake of turning on the cold water tap. Whereupon suddenly as if from no where a stream of cold water appeared through the downstairs roof directly below the bath. There was no obvious place where the water was coming from under the bath and when the cold was quickly turned off and the hot tap fitted there was no leak
This has obviously happened to somebody else in the past as there was an existing sagging patch in the plaster. It also happened to a plumber who was working on the sink. The second time he came, I think he might have avoided the problem by turning on both kitchen taps downstairs?
Pardon me if I appear ignorant but I would be grateful-prior to repairing the damage- for an explanation for the problem.
Is it just a matter of finishing the work on both bath taps before turning on the cold water or is there some more serious underlying problem.
