Maintenance, Repair, and Leak Detection
What the domain covers
Maintenance, Repair, and Leak Detection tests preventive checks, fault finding, leak location and safe repair of taps, valves, pipes, tanks and drains.
Core rules
- Preventive maintenance includes checking float valves, tap washers, exposed pipes, tank covers, supports and drain access chambers.
- Isolate and drain the affected section before repair; verify isolation at the fixture.
- Leak detection can use visual inspection, a water-meter test, dye testing in WCs, listening for flow, air or smoke testing of drains, and pressure testing of new pipework.
- Repair methods include replacing a washer or O-ring, tightening packing, reseating a tap, cutting out a damaged section, solvent-welding a plastic joint or re-threading a GI joint.
- Use the correct sealant: PTFE tape on threaded joints, solvent cement on compatible plastic joints, and rubber gaskets on compression fittings.
Worked example
A water meter keeps moving with every tap closed. Turn off the inlet to the WC and observe the meter; if movement stops, the fault is in the WC inlet or float valve. If movement continues, isolate other branches one by one. The reasoning is that a positive meter movement with no draw indicates a leak or passing valve; sectional isolation narrows the fault without opening walls.
Traps that cost marks
Overtightening plastic nuts, wrapping PTFE tape around a solvent-weld joint, using the wrong washer, repairing a pressure pipe with tape only, and failing to retest after the repair.