Isolating properly
Close the valve, then open the tap or outlet downstream and let it run dry. That does two things: it proves the valve actually closed, and it relieves the pressure that would otherwise be sitting behind the joint you are about to undo.
Have a bucket and a towel under the work before anything is loosened. There is always water in the hoses.
Know where your main stop is, before you need it
Find it now, and turn it while you are not in a hurry. A stop tap that has not moved in a decade is the one that will not move on the evening a hose fails, and knowing where it is has value independent of any job.
When a valve will not close
Stop. Forcing a seized valve breaks it, and it breaks on the pressurised side. At that point the job is no longer the one you started: it needs the supply off further upstream, and the valve itself has to be replaced.
The three kinds of work this site does not describe
Electricity in a damp room. New wiring, a socket, a hard-wired mirror or cabinet, an electric bidet seat where no socket exists. Bathrooms are zoned under national wiring rules that define what protection is required where and who may do the work. That is not a matter of confidence.
The pressurised side beyond an isolating valve. A failure there does not drip, it floods.
Powered waste. A macerator or lifting pump discharges waste water under power, with published limits on lift, horizontal run and inlet temperature. Installing one outside those limits is how a room floods, and the installation instructions are the authority on all of it.
What this site does instead
It reports what a manufacturer states a product needs, and points at the instructions and the national rules that govern the rest. A page that paraphrased an installation manual would be wrong more often than it was useful — which is why this one stops here.
Questions people actually ask
Is it safe to work on a tap with the mains still on?
No, and the isolating valve is not optional even for a small job. Water arriving under pressure into an open fitting is not a manageable situation once it starts.
What should I do if something starts leaking after a job?
Close the isolating valve first, then look. Diagnosing a joint while water is arriving is how a small leak becomes a wet cupboard, and the valve is two turns away.
Last reviewed 5 September 2026
