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020 4532 7773Every year, as temperatures rise through May and into summer, the conditions that favour Legionella development become more pronounced. Water systems that have managed perfectly well through the cooler months can begin to present a higher risk as ambient temperatures climb, storage tank temperatures drift upward, and any weaknesses in a building's water safety arrangements become more significant.
For business owners, building managers and facilities teams responsible for commercial properties in London, May is the point at which Legionella risk should be front of mind. Not because a problem is inevitable, but because the steps needed to manage the risk are straightforward when taken in advance and considerably more disruptive when taken in response to a problem.
This post sets out why summer is the peak risk period for Legionella, what commercial buildings need to have in place, and what action to take if your current arrangements need updating.
Legionella bacteria exist in most water systems at low, background levels throughout the year. The issue is not their presence but their concentration. When the right conditions come together, those background levels can increase to a point where they present a genuine health risk to anyone who inhales water droplets from the system.
The three conditions that drive Legionella growth are temperature, stagnation and nutrients. Summer affects all three.
Water temperatures in cold storage tanks, particularly those in roof spaces or poorly insulated plant rooms, rise significantly as ambient temperatures climb. Once the stored water moves above 20 degrees Celsius and towards the 20 to 45 degree danger zone, the growth rate of Legionella increases sharply.
Stagnation becomes more of an issue in the summer months for commercial buildings that have meeting rooms, guest facilities or other areas that see irregular use. Outlets that are not being flushed regularly allow water to sit in pipework for extended periods, creating pockets of warm, still water that are ideal for bacterial growth.
Nutrients, in the form of scale, sediment and biofilm, accumulate over time in systems that are not being properly maintained. A tank that was last cleaned twelve months ago may have a build-up that provides exactly the kind of environment where Legionella can multiply rapidly once temperatures rise.
ACOP L8, the Health and Safety Executive's Approved Code of Practice for Legionella control, sets out clear obligations for anyone responsible for a commercial building. Understanding what is required is the starting point for knowing whether your current arrangements are adequate.
Every commercial building with a water system is required to have a Legionella risk assessment carried out by a competent person. The assessment should be reviewed regularly and updated whenever there is a significant change to the system, the building or its occupancy.
If your most recent assessment is more than two years old, or if the building has changed since it was carried out, it should be reviewed now rather than later in the year.
The risk assessment feeds into a water safety plan, which sets out the specific control measures in place for your building and the monitoring and maintenance programme that supports them. The plan should be documented, kept up to date and accessible to anyone responsible for managing the water system.
ACOP L8 requires that monitoring and maintenance activities are carried out and recorded. This includes temperature checks on hot and cold water outlets, flushing records for infrequently used outlets, and inspection and cleaning records for any cold water storage tanks.
If your building does not currently have a documented monitoring programme in place, putting one together now, ahead of the peak summer risk period, is a practical priority.
When commercial buildings are reviewed for water hygiene compliance in the spring and early summer, the same issues tend to come up repeatedly. Being aware of them makes it easier to check whether any apply to your property.
The most frequently identified problems are:
Any of these issues, left unaddressed through the summer, increases the risk profile of the building and the liability of the duty holder.
If the description above raises any concerns about your current arrangements, there are four practical steps worth taking before the end of May.
If your cold water storage tank has not been professionally cleaned and inspected in the last twelve months, book it now. A professional clean removes the sediment and biofilm that provide nutrients for Legionella growth, and an inspection will identify any physical issues with the tank that need to be addressed before summer.
Our water tank cleaning service covers commercial and residential properties across London, with full laboratory testing and written reports provided on completion.
If your risk assessment is out of date or if the building has changed since it was last carried out, a fresh assessment will give you a clear and current picture of the risks in your system and what actions are needed. We offer same-day Legionella risk assessments across London, with full written documentation provided on the day.
Review whether all outlets in the building, including any that are used infrequently, are covered by a regular flushing programme. Any outlet that goes unused for more than a week should be flushed thoroughly before use. Where building usage means certain areas are consistently underused, a documented flushing schedule should be in place.
Where a risk assessment or tank inspection identifies contamination or a significant hygiene concern, a professional chlorination of the affected pipework or system may be required. Our chlorination services cover commercial and residential properties across London and can be arranged quickly where an urgent response is needed.
It is worth being direct about what is at stake. Legionnaires disease is a serious illness. Cases are most common in the summer months, and the buildings most often associated with outbreaks are those where water safety arrangements have been neglected or where a known issue has not been followed up.
For duty holders, the consequences of a failure extend beyond the immediate health risk. Enforcement action from the Health and Safety Executive, civil liability claims, reputational damage and, in serious cases, criminal prosecution are all possible outcomes where a duty of care has not been met.
None of that is inevitable or even likely for a building that has reasonable control measures in place. But May is the point in the year where those measures need to be confirmed and any gaps closed, not left for later.
At London Water Treatment, we work with commercial clients across London to support Legionella compliance throughout the year. Our services cover Legionella risk assessments, water tank cleaning and inspection, chlorination and ongoing monitoring, giving building managers a single point of contact for their water hygiene requirements.
If you are not confident that your current arrangements are adequate heading into the summer, the best time to address that is now. Contact our team today to discuss what your building needs. Call us on 020 4532 7773 or visit our Legionella services page for full details of what we provide.
