21 July 2022

Legionella in summer

As we move into the summer months and the sun begins to blare down, making us think of only two things; a nice cold drink and a place to sit down and relax. However, it is well known within the water industry that during the summer is the perfect time for bacteria like Legionella and other pathogens to rear their head and contaminate our water systems. 


Within this blog, we will be analysing Summertime Legionella, highlighting and discussing some of the key areas that duty holders should be looking out for as the temperature begins to rise.

Sun’s out and so is legionella:

We’re not the only ones who love the hot weather; Legionella thrives in the heat and is a form of pneumonia which can be fatal to people with underlying health issues. Legionella's optimum environment temperature for proliferation is between 20°C and 45°C - when warmer weather temperatures heat the water contained in the system and become the ideal environment for legionella to take hold and proliferate.


The Legionella Surveillance Reports created by Public Health England identified a clear increase in cases during the summer months rising from July to October. This could be for a number of reasons, transmission related to travel abroad, the warmer temperatures affecting your water system or even returning to a building which has been left unoccupied for a length of time. Whatever the reason,  during the Summer, it is more important than ever for duty holders to carry out regular water temperature inspections and maintain a good scheme of control so that water temperatures do not reach dangerous levels and ensure they are reporting any findings and keeping on top of their record keeping.

Summer Risks:


In the Summer months, universities, schools and accommodations are often left vacant, meaning that water systems are left stagnant. This increases the risk of Legionella once the new academic term starts. The same applies to tourism and water/ holiday parks - as they are used less frequently during the Winter months, water supplies could be left stagnant. If not properly handled and maintained, rising temperatures during the Summer months would create a breeding ground for Legionella.

Another aspect of Summer that should be carefully monitored is Staff Absences. An increased amount of staff absence could mean that fewer staff are available to help maintain safe levels of protection. The best way to deter this is to ensure that there are enough trained employees working at all times to maintain the water system and appropriately handle any problems that could occur.

Your duty as duty holder:

Summer is a crucial season for Duty Holders to stay on top of preventing their properties' water systems from being contaminated with pathogens like Legionella. As a Duty Holder, it is your responsibility to monitor or seek out professionals such as SMS Environmental to ensure that you can prevent bacteria proliferation and maintain a high standard of safety within your properties.  


Duty Holders are required to understand and follow the following legal frameworks:

  • The Health and Safety at Work etc Act 1974
  • The Management of Health and Safety at Work Regulations
  • More specifically, the Control of Substances Hazardous to Health Regulations 2002 (COSHH) and;
  • HSE Guidance, The Approved Code of Practice: Legionnaires’ disease: The control of Legionella bacteria in water systems (ACoP L8)




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