Control Measures to Manage Legionella Risk in Summer

Summer is finally here in Ireland. A rise in mercury means increased use of many water applications. Air conditioning units and associated cooling towers, for example, are in greater demand in the summer and swimming pools are visited more frequently.

While many would be enjoying the warm weather, duty holders and responsible persons must be aware of the heightened and hidden risk of Legionella in water sources and systems.

The summer months are notorious in terms of acknowledged spikes in reports/confirmed cases of Legionnaires’ disease outbreaks, with August being the key date on the calendar.

In this blog, we discover how legionella risk is influenced by warm weather and what businesses need to do to fulfil their legal duties.

Increased Legionella Risk in Summer

Statistics show that summer is a peak time for Legionnaires’ disease infections. Legionella surveillance reports issued by Public Health England summarize the total reported and total confirmed cases on legionella on monthly basis.

A trend can be easily observed with cases of Legionnaires’ disease in the UK usually increasing during the summer months, peaking between July and September.

While Legionella bacteria are ubiquitous in freshwater sources, an outbreak could occur when provided with favourable growth conditions.

Legionella grows and thrives in temperatures ranging from 20°C to 45°C. As the temperatures start to rise in summers, the incoming mains water may be in this danger zone.

Another factor that contributes to the growth and proliferation of legionella bacteria in water systems is the movement of water. Many buildings – whether homes or workplaces – can see a drop in water usage as people go away on holiday in the summers. Because of these quieter periods, stored and stagnant water can become a breeding ground for Legionella bacteria, especially when temperatures start to rise.

The increased use of air cooling systems during the summer months can also be a concern. In particular, the use of portable evaporative air coolers, that don’t get used for much of the year and are not properly maintained can create problems.

How to Manage Legionella Risks in Summer Months

It has been particularly noticeable during the heatwave that the ambient temperature of mains water is warmer than normal.

For this reason, the monitoring and controlling of water temperatures to ensure the water is outside of the Legionella growth band is vital.  Keep all hot water systems at above 60°C, with water outlets maintained at a minimum of 50°C; in healthcare environments, this should be 55°C. Likewise, cold water should be kept below 20°C, wherever possible.

Check the temperature of both hot and cold water regularly (ideally weekly) and record your findings. Lagging on tanks and pipes can be used to help regulate temperatures if necessary.

Water outlets that are infrequently used should be flushed regularly to avoid stagnation. Evaluating the usage of the water systems – in the Legionella risk assessment and ongoing following the risk assessment – will determine how regularly the outlet should be flushed.  As a guide, any outlet that has not been used for a week or longer should be flushed for at least 5 minutes.

Water tanks, pipes and adjoining/interconnected outlets for recognised water sources remain clean at all times and keenly observed for any signs of a build-up of bacteria within the various structures of an existing system. Monitoring and subsequent servicing will include a raft of tasks, such as water chlorination, tackling dead legs, showerhead sterilisation, TMV servicing and hot and cold water tank cleaning.

Other steps which can be taken to prevent the risk of legionella include downsizing water tanks (to minimise volumes of stored water), installation of delayed action float valves (to reduce volumes in existing tanks), removal of storage where mains supply can match demand.

Ensure Safe & Compliant Water Systems All Year Round

Vigilance is of course important, but the aspect which underpins the entire process when it comes to protecting against legionella bacteria is the rolling out of an up-to-date control scheme.

For companies of all shapes and sizes, legionella compliance must always start with a legionella risk assessment and by the appointment of a competent individual who is knowledgeable in this critical element of health and safety.

The team at Water Treatment Ireland Ltd helps those in control of the premises to effectively manage the hidden risks in the building and fulfil their duties regarding the control of legionella bacteria.

If you need professional help with any aspect of water hygiene now or at any time of the year, we can help. Contact us for a free consultation.