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Tips To Help Estate Managers Better Manage The Risk Of Legionella

If you are an employer, landlord or another individual in control of a commercial or residential premises, it is your responsibility – as set out by the Health and Safety at Work Act 1974 – to adopt measures to reduce the risks of legionella exposure on-site.  

But what is legionella, and why should you take its risks so seriously?

What is legionella?

Legionella is the name given to the bacteria that can be present in droplets of water from the likes of air conditioning systems and hot tubs. The inhalation of such water droplets can lead to the lung infection, Legionnaires’ disease, which – while uncommon – can be very serious, and even fatal.

The name of the condition arises from the first known outbreak in 1976, when an American Legion convention in Philadelphia – attended by more than 2,000 members of the Legion – led to 182 infections and 29 deaths.

Why should a business be concerned about legionella?

One obvious reason for your business to be concerned about legionella is, of course, the moral one. With legionella being a naturally occurring bacteria that lives in water, it only potentially takes certain favourable conditions to arise within buildings for the bacteria to thrive.

One of the particular issues with legionella is its relative invisibility. While individuals responsible for managing the health and safety risks in business buildings are likely to immediately notice the risks presented by such problems as smashed windows and blocked fire exits, hazards contained within a premises’ water systems tend to be much less visible. They can be hidden away in such areas as under floors, behind furniture and in ceiling voids.

This lack of visibility can easily allow for the legionella bacteria to proliferate and colonise a premises’ water system if precautions are not taken to negate this. This might mean that when someone present in your buildings next flushes a toilet or runs a tap, the very fine water droplets released – known as aerosol – could expose them to legionella.

Another compelling reason for any business to take the legionella risk seriously, is the legal one. An extensive legal and regulatory framework has arisen over the decades to help tackle legionella risks in commercial properties. This includes the likes of the Control of Substances Hazardous to Health Regulations 2002 (COSHH), which sets out actions for assessing, preventing and controlling the risks bacteria like legionella can present.

Of similarly great significance is the book Approved Code of Practice (ACOP): Legionnaires’ disease: The control of legionella bacteria in water systems. A free copy of this document can be downloaded from the Health and Safety Executive (HSE), and it aims to assist duty holders in their efforts to comply with their legal duties in relation to legionella.

What steps should you take to manage the risk of legionella?

Your legionella risk management strategy should be based on the findings of a risk assessment that will help you to pinpoint and tackle areas of your property where there could be a danger of exposure to the bacteria. If it is not possible to eliminate legionella exposure risk, controls must at least be implemented and maintained to lower this risk.

1. Identify and assess the risk

The first step to greatly reducing the chances of your buildings’ users contracting Legionnaires’ disease, is arranging for a risk assessment to be conducted by a competent person.

Competency is subjective, but it needs to be someone who possess sufficient competence, authority, experience and the necessary knowledge and skills in relation to the premises’ water systems.

You may decide to carry out the risk assessment yourself if you are only responsible for a small property with a simple hot and cold-water system. For larger and more complex sites, in all likelihood, it is more prudent to leave the risk assessment to a qualified external professional or consultant.

2. Manage the risk

Once a risk assessment has been carried out, and the risk of legionella on your premises has been identified and assessed, it will be time to begin actively managing that risk.

Duty holders are required, in accordance with the aforementioned ACOP document, to appoint a ‘Responsible Person’, whose role it will be to control the risk posed by legionella bacteria on a day-to-day basis. This will involve such tasks as implementing the recommendations that should have arisen from the risk assessment, as well as choosing the contractors who will maintain the system, and arranging for all necessary routine monitoring.

3. Prevent and control

There are various measures that can be adopted on business premises to help make it much less likely that the users of the buildings will be exposed to legionella bacteria.

Ideally, duty holders should be aiming to eliminate the conditions allowing for the growth and dispersal of legionella bacteria, however, there may be instances in which elimination is not a realistic objective – in which case, measures should be implemented to adequately control the risks.

One such measure could be controlling the water temperature, which – below 20 degrees Celcius – will keep the bacterium alive but prevent it from multiplying. Heightening the water temperature to above 60 degrees Celcius, meanwhile, will kill the bacteria.

As a duty holder, you may also look to put in place strategies like maintaining the utmost cleanliness of the water and system, ensuring there is sufficient flow to prevent water stagnation, and decreasing the release of water spray.

4. Keep records and evidence ‘best practice’

The maintenance of adequate records will also greatly aid your efforts to manage the legionella risk on your premises. This should begin with keeping a record of every risk assessment, so that you can refer back to it for evidence of the issues identified and what actions have been undertaken to lower the risk.

Keeping a water log book for your building can provide you with a record of water temperatures and other checks, to help ensure you are taking responsible steps to minimise legionella risks on-site.

If you need help to manage your legionella risk call ACMS UK on 0115 922 0600 or email