Finding and using isolation points before you start, handling a leak or burst safely, and thawing a frozen pipe without damage.
Plan the isolation before starting a repair. Knowing which isolation valve or switch controls the work area saves time if a leak or other fault develops, but never reach it in an unsafe way.
Trace the supply
Establish the fault, the agreed scope and the relevant water, gas and electrical isolation points. Check access and the needs of occupants before interrupting services. Show the customer the water shut-off and its actual operation: a conventional screw-down stop tap closes clockwise, while other valves have different actions. Use gentle movement and avoid force.
The incoming mains stop tap shuts off new mains water. It does not stop water already feeding from a storage cistern or drain a cylinder. With no valve at the fitting, trace an effective upstream isolation point for the actual supply, then release pressure and check that flow has stopped before disconnecting.
An active leak
Where the appropriate valve is safely reachable and there is no electrical hazard, stop work and isolate the affected supply. Contain residual water when safe, then assess the repair. A bucket is not a reason to continue dismantling with the supply live.
If water is near sockets, appliances or a wet consumer unit, keep people away and obtain competent electrical help. Do not touch a wet switch or wade through water to reach it. Shut off water only from a safely accessible position. Electrical and structural hazards take priority over protecting the finishes.
A valve that will not isolate
Do not use a long bar or flame on a seized stop tap. If gentle movement fails, arrange another suitable isolation point and repair or replacement. An external valve may serve other properties or require the water supplier’s involvement; establish the correct procedure first.
A closed valve handle does not prove that water has stopped. Water already in a higher part of the isolated section can drain out, but a passing valve or connected cistern can keep supplying it. Trace the feed, establish effective isolation and drain the remaining water through a suitable outlet. Confirm that flow has ceased before opening the repair point; an open drain does not isolate anything while fresh water keeps coming in.
Frozen pipework
If a pipe is suspected frozen, safely isolate its supply and open the affected tap to allow thawing water to escape. Warm it gradually with warm towels or a wrapped hot-water bottle. Avoid boiling water, naked flames and electrical heating equipment where it could contact water.
Watch for splits or leaks as the ice melts. Check before cautiously restoring the supply, and leave it off if damage is found. Obtain help where the section is inaccessible or the work would expose anyone to electrical, access or other hazards.