Repair, Maintenance and Leak Detection: Finding and Fixing Losses
What this domain tests
This domain tests planned and breakdown maintenance, leak detection methods and safe repair. Expect questions on pressure testing, visible and hidden leaks, valve isolation and preventive schedules.
Core rules and concepts
- Maintenance is planned (inspection, cleaning, replacement) or breakdown (emergency repair). Records of both guide future work.
- Leak detection methods: visual inspection, pressure test, acoustic listening, dye test, smoke test and thermal imaging.
- A pressure test isolates a section, pressurises it and watches for a drop; a falling gauge indicates a leak.
- Repair methods include replacing a section, re-making a joint, tightening a gland, or using a proprietary clamp for a temporary fix.
- Isolate and drain before repair; verify that the correct valve closes.
- Hidden leaks show as damp patches, mould, high water bills or a running meter with all taps closed.
Worked example
A 10 m supply section is pressurised to 6 bar. After 30 minutes the gauge reads 4.5 bar with no draw-off. The 1.5 bar drop indicates a leak. The reasoning: temperature change can cause a small drop, so isolate the section and repeat; a repeatable drop confirms a leak. Then divide the run with isolation valves to narrow the location before excavating.
Traps that cost marks
- Tightening a joint until it cracks instead of remaking it.
- Repairing without isolating and draining.
- Ignoring a small repeatable pressure drop.
- Confusing a meter movement caused by a cistern refill with a leak.
- Patching a buried leak without checking the cause.