Maintenance, Fault Diagnosis and Repair of Plumbing Systems
Domain focus
This domain tests fault diagnosis, repair and maintenance of plumbing systems. It covers leaks, low pressure, blockages, noisy pipes, poor hot water, running WCs and failed valves, plus post-repair testing and records.
Core rules
- Gather the symptom history: when it occurs, which fixtures, and what changed recently.
- Isolate and drain before repair; confirm the correct valve and tag it.
- Work systematically: source, distribution, fixture. Check pressure and flow at several points.
- Use the right test: gauge for pressure, dye for WC leakage, air or smoke for drains, camera for buried blockages, flow test for restriction.
- Repair with compatible materials; replace washers, cartridges, seals and damaged sections rather than forcing.
- Retest, flush, clean up and record the fault, action and parts used.
Worked example
A running WC is diagnosed with dye in the cistern: if coloured water appears in the pan without flushing, the flush valve or flapper is passing. Check the seat and replace the seal. The reasoning separates inlet valve overflow from flush valve leakage.
Traps
Changing parts without diagnosis; failing to isolate; using a drain snake roughly in plastic; leaving debris in a trap; no retest; no record of the repair.