In this blog, we share some experiences of situations that can increase the risk of Legionella bacteria growth and what could have been done to prevent them.
Why controlling Legionella bacteria in education matters
Have you or your organisation ever been subject to an HSE investigation due to a Legionella outbreak? It can be a daunting experience that triggers a lot of internal Q&A’s where many ‘hope that it’s not us’ and ‘have we done all of the things we should have?’ The process moves very quickly, causing some to panic. The actual need to control Legionella bacteria is to prevent people from coming to harm, and not just to limit reputational damage.
If you have reached the position of investigation, it is probably too late to affect any of the outcomes. However, even if your facility is not the actual source of the outbreak, you could still be prosecuted for not fulfilling your legal responsibilities.
A case we recall was one of a cricket team, a mixed-age group, who played at various locations. Two of the team reported illness to their separate GPs, who registered the symptoms as possible ’legionnaires’ disease’ (which is a notifiable disease). Public Health England investigated and established that the two individuals were known to each other via the cricket team. The cricket club shared the locations where both had played, which triggered the Local Authorities to take Legionella samples. One location was an educational sports facility, not the source of the outbreak, but there were some anomalies that the HSE investigated anyway.
Common Mistakes and How to Avoid Them
Schools, colleges, and Universities bring a diverse mixture of water-based systems, which can be subject to seasonal changes that bring changing risks. Whether it be a water feature, a staff kitchenette, an outside tap, a hall of residence, a complex laboratory building, or a sports facility, there is a legal responsibility to operate and manage each water system so that the in-built hazards are controlled to a safe level.
Inadequate/outdated Legionella risk assessments (LRA): Each water system requires a Legionella Risk Assessment that informs on the true level of risk. The LRA should be reviewed on a regular basis, which is dependent on the risk. Take a small office block that has mains cold water and point of use water heaters serving just toilet and kitchenette facilities, this could be reviewed every 3 years, say. However, this is subject to other factors such as user susceptibility, regular continued use, and an implemented Legionella written scheme of control e.g., maintenance, cleaning, temperature checks, and usage evaluation.
If there is a significant change, say a shower being added or hybrid working implemented, the LRA must be updated to reflect the changes and inform of any changes that amend the written scheme.
Your Legionella risk assessment should be to a standard that reflects the complexity of your water system, with BS8580 being the minimum standard. Further accreditations, such as UKAS ISO/IEC 17020 are available that reassure that the British Standard has at least been met.
Inadequate design risk assessments: For any new projects, a project design review should be conducted to inform on the selection of components, fixtures, and fittings. Collaborative working between the Architect, Mechanical Designer, Client, and the Operations Team should ensure that designs are rational and reflect the true risk and not the perceived risk.
All too often, future-proofing and poor practices pass from one project to the next. Often, thermostatic control of hot outlets on wash hand basins is installed without considering the actual risk. A scald risk assessment could negate the need for thermostatic control, reducing the Legionella risk and saving Cap Ex and Op Ex. Equally, installing outlets or connections for the ‘just in case’ scenario should be avoided.
A specific Project Water Safety Group should be formed, and a Project Water Safety Plan developed. BS8680:2020, advises on the requirements.
Operating and Maintenance Manuals / Legionella Written Scheme of Control: Designers and Contractors have the responsibility to provide Operating and Maintenance (O&M) manuals to advise how the facility, including water systems, should be operated and maintained.
Architectural, mechanical services, and building management/control systems information should be consolidated and compiled within a specific domestic water services section that provides relevant information for the Legionella written control scheme. Asset information should be concise and inclusive so that the asset management teams can transfer the relevant information into their PPM planners.
Training / Competence: All too often, it can be assumed that ‘it’s someone else’s job’ to deliver the various tasks. The management and control of water systems could require a multi-disciplined team with the correct level of competence for the roles that they are to perform. A few experiences that need to be addressed are:
- A project team for a multi-million-pound laboratory building, apart from the Mechanical Designer, were from an electrical background, and this included the Clerk of Works. Whilst there was some familiarisation with water systems, nobody had attended at least a Legionella awareness training course.
- I was told that ‘CAT5 (laboratory) water systems do not matter as they have backflow protection’. Legionella bacteria do not know what type of water system they are in. If the conditions are such that the bacteria can proliferate and water is discharged through an outlet, you are legally required to control the hazard. ACoP L8 supports you with this.
- BMS teams making decisions without realising the consequences. One being the hot water return sensor to the HWS generator was omitted/removed to reduce alarms i.e., if the water temperature dropped below 50oC!! The other was automated pasteurisation, raising the HWS temperature to 70 °C, which was included in the control logic for new student accommodation, which took place at 0100 hours for one hour. Pasteurisation is a disinfection method, optional if failed sample results have been returned, and must be a controlled process; otherwise, the scald risk is significantly increased to a dangerous level.
Operational Management: Often, the simple tasks are the most effective control of Legionella, but equally, they could be the weakest link, which requires auditing to check that the teams/individuals assigned to the task are fulfilling their obligations. Before staff are engaged, they should have training for the task and follow a standard operating procedure.
- Usage evaluation. Theoretically, most outlets should be used through usual occupancy patterns e.g., Monday to Friday, leaving just a few outlets that require dedicated flushing. Individuals should be assigned to this task (responsible person) on a weekly basis, and periods of low / no use that require increased flushing activity should be noted. Also, there is a need to appoint a deputy for the task should there be any absence.
- Prevention of scale buildup is significant and should be a routine task.
- Temperature monitoring monthly, focusing on sentinel points (advised in your LRA) and a selection of other outlets, is required and must be recorded in the logbook.
Record keeping: I’ll refer you back to the start of this blog, the HSE investigation. To demonstrate that your obligations have been fulfilled, it is very important to keep signed and dated records for any activity that is part of operating, maintaining, and changing your water systems. This includes staff records and their training records. If there is ever a need to demonstrate that you have taken your responsibility seriously, these records will be crucial in the process.
Feel free to reach out if you have any questions about the issues mentioned above or if you would like to consult with one of our experts on water hygiene.
Editor's Note: The information provided in this blog is correct as of the date of original publication – May 2026
© Water Hygiene Centre 2026
