WATER HYGIENE & SAFETY


A Legionella control case study – when routine fails


Speaking during an update on the activities of the various IHEEM Technical Platforms at July’s 2025 IHEEM Authorising Engineers conference, Harry Evans, an IHEEM-Registered Authorising Engineer (Water) discussed a past experience in his AE capacity advising a school on addressing a challenging Legionella issue. In a cautionary tale, he described how he, the school’s own engineer, and its management, soon realised the school’s caretaker had failed to complete many of the essential preventative, and subsequently, remedial tasks he had claimed to have undertaken, with disastrous results.


After years in complex, high-pressure hospital environments, a newly appointed hospital engineer and long-serving Responsible Person (RP) is drawn to the promise of a quieter role at Flushoaks Primary School – a fictional but representative single-storey facility located somewhere in the south of Scotland. The school serves just under 300 pupils, and on paper at least, presents a textbook example of a ‘low-risk’ building. There are no showers, with a direct-fired water heater handling hot water generation, cold water stored in a 1200-litre tank, and with the site incorporating just 60 outlets and a single external bib tap. Upon arrival, the engineer anticipates an environment


of procedural ease and reduced stress. His first routine question to colleagues feels innocuous: “How many Legionella samples do you take each year?” The response was jarring: “What are Legionella samples?” Note: This is not a hospital environment, and routine


Legionella sampling is not typically required. Primary schools lack augmented care areas, control failures, or high-risk features, that would necessitate regular testing.


Initial inspection and immediate escalation Alarmed by the lack of awareness among staff, the engineer undertakes a visual inspection of the cold-water storage tank. What he finds is far removed from the serene simplicity he had imagined: significant biofilm formation, layers of debris, and substantial sediment. It’s a scene that triggers deep professional concern and an instinctive escalation. The engineer contacts a trusted water treatment specialist – one with whom he had collaborated previously in hospital settings. Twelve water samples are swiftly collected from key outlets across the building. When the results return, they indicate systemic contamination: Legionella is detected in eight of the 12 outlets sampled. The nature and spread of contamination demand decisive action. The water treatment specialist recommends: n A full clean and disinfection of the cold-water tank. n A complete system-wide disinfection of the building’s water services.


The engineer agrees immediately. There is no room for compromise. Post-treatment sampling is undertaken, and results appear encouraging; all outlets test clear. A sense of control, albeit fragile, begins to re-emerge.


Monitoring, recurrence, and mounting concerns The engineer recommends that monthly water quality monitoring is introduced, as recommended by the water treatment specialist, encompassing testing for: n Legionella species.


Below, left to right.


Figure 1: The former hospital engineer’s expectation that moving to take up an engineering role at the primary school would mean a quieter and considerably less stressful working week was soon confounded.


Figure 2: On an initial visual inspection of the cold-water storage tank soon after arriving at the school, the engineer finds significant biofilm formation, layers of debris, and substantial sediment.


Figure 3: The engineer contacts a trusted water treatment specialist – with whom he had collaborated previously in hospital settings – and 12 water samples are swiftly collected from key outlets across the building.


September 2025 Health Estate Journal 55


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132