Staff at a commercial trade supplies unit reported water leaking from somewhere in the upstairs WC facilities. The leak had been observed the previous day, but by the time our engineer attended, the exact source remained unclear and no active water was visible. Such intermittent leaks present particular diagnostic challenges, as the fault may only manifest under specific conditions that are difficult to replicate on demand.
Intermittent water leaks in commercial premises can indicate several underlying issues: usage-related faults that only occur during specific operations, pressure-dependent problems that appear when system pressure fluctuates, temperature-related failures where seals or joints fail when hot water expands pipework, overflow conditions during heavy usage periods, or concealed pipework issues where leaks within walls or floor voids take time to become visible at surface level.
Investigation Methodology
Our plumbing engineer attended site and implemented a comprehensive assessment protocol designed to either locate the fault definitively or confirm the system’s integrity through methodical elimination.
Visual Inspection
The initial assessment involved detailed visual inspection of all accessible plumbing components in the WC area. The engineer examined the toilet pan and cistern connections, basin waste and supply pipework, floor surfaces for signs of water damage or staining, wall surfaces for damp patches, and all accessible inspection hatches. No visible evidence of active leaking was present during this initial inspection phase.
Stress Testing Protocol
With no visible leak present, the engineer conducted stress testing designed to replicate conditions that might trigger the reported fault. This approach recognises that intermittent faults often require specific conditions to manifest.
The basin was run continuously to test supply connections under sustained flow, with monitoring of waste pipework during extended drainage periods. Trap seals and waste connections were observed under continuous flow conditions that would exceed normal usage patterns.
The WC received particular attention, with the toilet flushed eight to ten times in rapid succession—far exceeding normal usage intensity. Throughout this process, the engineer monitored cistern refill operation and overflow function, checked the pan-to-soil connection under repeated flushing stress, and observed for any seepage around the base or rear connection.
Concealed Pipework Examination
Access panels were opened to inspect concealed pipework and connections that would not be visible during normal inspection. The engineer examined pipe joints and fittings behind the access hatches, checked for any moisture accumulation or water staining that would indicate historical leakage, and verified that all connections remained completely dry throughout the stress testing process.
