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?"