Legionnaires’ disease: why water management is key in prevention

Legionnaires’ disease is a potentially fatal infection similar to pneumonia that is caused by Legionella bacteria.

This type of bacteria is found in most natural water sources and can be airborne through water droplets. However, in man-made water systems the conditions are optimal for Legionella, therefore growing and spreading.

This is a cause for concern in any business containing a water system and rightly so. With its potentially fatal effects, Legionella should be tested regularly. Water management is the key to protecting your workforce and users of your buildings.


Is Legionella testing a legal requirement?

There are several pieces of legislation laid out to help building owners or their designated ‘responsible person’ to understand their obligations. These pieces of legislation include:

  • The Health and Safety at Work etc Act 1974
  • The Management of Health and Safety at Work Regulations 1999
  • The Control of Substances Hazardous to Health Regulations 2002
  • Approved Code of Practice: Legionnaires Disease (ACoP L8)


What is the most important guidance?

Whilst all of these pieces of legislation are relevant. The last one (Approved Code of Practice: Legionnaires Disease (ACoP L8)) is the most appropriate to follow when managing Legionella risks. Employers and business owners should make themselves familiar with the guidance it provides.

The ACoP L8 helps through managing water to comply with legal obligations including:

  • Assessing water system risks
  • Managing associated risk
  • Implementing and monitoring precautionary methods
  • Documenting said methods


What must I do as the responsible person?

As a business owner you can manage this process yourself (if sufficiently trained and qualified). Alternatively, you can nominate a ‘responsible person’. This person can be an employee or an external water hygiene specialist.

The key contact in preventing Legionnaires disease must complete a formal assessment (in line with BS 8580:2010) of the site which includes water storage and water transport systems. You can read more about this here. They must also create a Legionella risk management plan that documents how to reduce or remove any risks of Legionella in water systems.


How can good water management prevent Legionnaires’ disease?

As a bare minimum, there must be temperature checks put in place to minimise spread of this microbe. Legionella bacteria have optimal conditions between 20–45°C, therefore water should be below 20°C or above 60°C (to ensure it remains dormant).

Other water management controls to prevent Legionella growth or spread include:

  • Distributing hot water only as a temperature of 50°C or above
  • Routine checks of storage and distribution temperatures
  • Regularly flushed and descaled shower and bathing equipment
  • Biocide treatments for tricky areas such as cooling towers
  • Frequent water testing and analysis


How to minimise the risk of Legionnaires disease?

There are several methods of maintaining a low level of Legionella, therefore decreasing the risk of Legionnaires disease developing in the vulnerable. The main things include:

  • Removing any corrosion in water transport systems such as pipes
  • Recycling the water that has been in the system too long
  • Removing any unused pipes that debris could build up in
  • Checking for a build-up of biofilm as this creates better conditions for the bacteria
  • Regularly dosing the system with a biocide


From this we hope you can appreciate that there is no one-size-fits-all in protecting against Legionnaires disease. However, managing water effectively can increase the changes of ensuring your water system is safe.

Your building’s responsible person must follow the guidance in the appropriate legislation to ensure they are doing as much as they can to prevent Legionella bacteria and save lives.