Legionella Risk Assessments

Principal Hygiene - Your Local Clinical Waste Service Company

What services do we offer? 

Principal Hygiene provide Legionella Risk Assessments, Legionella control services, Legionella sampling, Legionella monitoring and remedial services.

What is legionnaires’ disease?

Legionellosis is the collective name given to the pneumonia-like illness caused by legionella bacteria. This includes the most serious legionnaires’ disease, as well as the similar but less serious conditions of Pontiac fever and Lochgoilhead fever. Legionnaires’ disease is a potentially fatal form of pneumonia and everyone is susceptible to infection. However, some people are at higher risk, including:

• people over 45 years of age;
• smokers and heavy drinkers;
• people suffering from chronic respiratory or kidney disease; and
• anyone with an impaired immune system.

Where are legionella bacteria found?

The bacterium Legionella pneumophila and related bacteria are common in natural water sources such as rivers, lakes and reservoirs, but usually in low numbers. Since legionella bacteria are widespread in the environment, they may also contaminate and grow in purpose-built water systems such as cooling towers, evaporative condensers, hot and cold water systems and whirlpool spas.

Are there legionella risks in my workplace?

Any water system that has the right environmental conditions could potentially be a source for legionella bacteria growth. There is a reasonably foreseeable legionella risk in your water system if:

• water is stored or re-circulated as part of your system;
• the water temperature in all or some part of the system is between 20–45°C;
• there are sources of nutrients such as rust, sludge, scale and organic matters;
• the conditions are likely to encourage bacteria to multiply;
• it is possible for water droplets to be produced and, if so, if they can be dispersed over a wide area, eg showers and aerosols from cooling towers; and
• it is likely that any of your employees, residents, visitors etc are more susceptible to infection due to age, illness, a weakened immune system etc and whether they could be exposed to any contaminated water droplets. Health and Safety Executive Legionnaires’ disease:

The most common places where legionella can be found include purpose-built water systems, cooling towers, evaporative condensers, hot and cold water systems and spa pools. There are also a number of other systems that may pose a risk to exposure to legionella, eg humidifiers, air washers, emergency showers, indoor ornamental fountains etc.

What are my duties?

Under general health and safety law, as an employer or person in control of a premises (eg a landlord), you have health and safety duties and need to take suitable precautions to prevent or control the risk of exposure to legionella. Details of the specific law that applies can be found in part 1 of Legionnaires’ disease: The control of legionella bacteria in water systems.

Carrying out a risk assessment is your responsibility and will help you to establish any potential risks and implement measures to either eliminate or control risks. You may be competent to carry out the assessment yourself but, if not, you should ask someone with the necessary skills to conduct a risk assessment. This can be done by someone from within your own organisation or from someone outside, eg an external consultant.

How do I identify and assess sources of risk?

To identify the risks in your water system you, or a competent person who understands your water systems and any associated equipment, should establish any possible exposure to legionella risks, as listed above, as part of a risk assessment.

Your risk assessment should include:

• management responsibilities, including the name of the competent person and a description of your system;
• any potential risk sources;
• any controls currently in place to control risks;
• monitoring, inspection and maintenance procedures;
• records of the monitoring results, inspection and checks carried out; and a review date.

If you decide that the risks are insignificant and are being properly managed to comply with the law, your assessment is complete. You will not need to take any further action, but it is important to review your assessment periodically in case anything changes in your system.

How do I manage the risk?

As an employer or person in control of premises, you must appoint someone competent to help you comply with your health and safety duties, eg take responsibility for managing the risks. A competent person is someone with the necessary skills, knowledge and experience to manage health and safety, including the control measures. You could appoint one, or a combination of:

• yourself;
• one or more workers; and/or
• someone from outside your business.

If there are several people responsible for managing your risks, eg because of shiftwork patterns, you need to make sure that everyone knows what they are responsible for and how they fit into the overall risk management programme.
If you decide to employ contractors to carry out water treatment or other work, it is still the responsibility of the competent person to ensure that the treatment is carried out to the required standards. Remember, before you employ a contractor, you should be satisfied that they can do the work you want to the standard that you require.

How do I prevent or control the risk?

You should consider whether you can prevent the risk of legionella in the first place by considering the type of water system you need, eg consider whether it is possible to replace a wet cooling tower with a dry air-cooled system. The key point is to design, maintain and operate your water services under conditions that prevent or adequately control the growth of legionella bacteria.

You should, as appropriate:

• ensure that the release of water spray is properly controlled;
• avoid water temperatures and conditions that favour the growth of legionella and other micro-organisms;
• ensure water cannot stagnate anywhere in the system by keeping pipe lengths as short as possible or by removing redundant pipework;
• avoid materials that encourage the growth of legionella. The Water Fittings and Materials Directory3 references fittings, materials, and appliances approved for use on the UK Water Supply System by the Water Regulations Advisory Scheme);
• keep the system and the water in it clean; and
• treat water to either kill legionella (and other microorganisms) or limit their ability to grow.

If you identify a risk that you are unable to prevent, you must introduce appropriate controls. You should introduce a course of action that will help you to control any risks from legionella by identifying:

• your system, eg developing a written schematic;
• who is responsible for carrying out the assessment and managing its implementation;
• the safe and correct operation of your system;
• what control methods and other precautions you will be using; and
• what checks will be carried out to ensure risks are being managed and how often.

What records do I need to keep?

If you have five or more employees, you have to record any significant findings, including any groups of employees identified by it as being particularly at risk and the steps taken to prevent or control risks.

If you have less than five employees, you do not need to write anything down, although it is useful to keep a written record of what you have done.

Records should include details about:

• the person or people responsible for conducting the risk assessment, managing, and implementing the written scheme;
• any significant findings of the risk assessment;
• the written control scheme and its implementation; and
• the results of any inspection, test or check carried out, and the dates.

This should include details about the state of operation of the system, ie in use/not in use.

These records should be retained throughout the period for which they remain current and for at least two years after that period. Records kept in accordance with the last bullet point above should be retained for at least five years.

Do I have any other duties?

Under the Notification of Cooling Towers and Evaporative Condensers Regulations 1992,4 you must notify your local authority, in writing, if you have a cooling tower or evaporative condenser on site and include details about where it is located. You must also tell them if/when such devices are no longer in use. Notification forms are available from your local environmental health department.

If you have a case of legionellosis in an employee who has worked on cooling towers or hot water systems that are likely to be contaminated with legionella, you must report this under the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations (RIDDOR).

Are there Legionella risks in my workplace?

There may be a risk of exposure to Legionella if your workplace or premises has one of the following:

• a cooling tower or evaporative condenser
• dry/wet cooling systems (sometimes referred to as hybrid or adiabatic coolers)
• hot and cold water systems
• spa pools
• other potential risk systems

Do I need to have a Legionella risk assessment?

Yes, if you are an employer or a person in control of premises, that includes privately rented residential properties as well as commercial properties, you must have a legionella risk assessment undertaken to identify the possible risks posed by legionella to the people within that property.

As an employer or a person in control of premises, you must appoint a competent person or persons to undertake a legionella risk assessment. A competent person is someone with the necessary skills, knowledge and experience to be able to undertake a legionella risk assessment with accuracy and efficiency. If you are not able to do this yourself, you must employ a subcontractor with the relevant credentials.

If I am not storing hot or cold water in my system, do I need to carry out a risk assessment?

Yes. There may be other factors within your system that increase the risks of legionellosis, eg deadlegs, showerheads and/or long runs of pipe work containing warm water. A risk assessment should also consider anyone who could be potentially exposed to any legionella bacteria in your system, and particularly groups that are at a higher risk of contracting legionellosis.

How do I control the risks from legionella in my water system?

The key point is to design, maintain and operate your water services under conditions that will either prevent or adequately control the risk from legionella bacteria. It is important that you either have, or have access to, competent help to fulfil these obligations. 

If you identify a risk that you are unable to prevent, you must introduce appropriate controls. You should introduce a course of action that will help you to control any risks from legionella.

Who can be appointed to test or monitor legionella?

Testing of water quality may be carried out by a service provider, such as a water treatment company or consultant, or by the operator, provided they are trained to do so and are properly supervised. The type of test required will depend on the nature of the water of the system.

How do I test or monitor legionella from my water system?

Where monitoring for legionella is considered appropriate, the sampling method should be carried out in accordance with BS7592. Water samples should be tested by a UKAS-accredited laboratory that takes part in a water microbiology proficiency testing scheme such as that run by Public Health England.

How often should I test water for Legionella?

It depends on the system that you have and the outcome of your risk assessment.
There may be circumstances where testing for legionella is necessary eg where there is doubt about the efficacy of the control regime or where recommended temperatures or disinfection concentrations are not being consistently achieved.

Is it necessary to clean and disinfect my water system?

It is important to maintain the cleanliness of your water system. The mechanisms and frequency for doing this will depend on the system you have and whether cleaning or disinfecting is being done routinely or because of a problem identified during monitoring. The frequency and method of routine cleaning and disinfecting should be identified within your risk assessment.

I am a private landlord; do I need to have a Legionella Risk Assessment for my property?

Yes. You have a duty of care to ensure the safety of your tenants. It is a legal requirement under health and safety law to have a valid Legionella Risk Assessment undertaken on your property.

I am a private landlord; my property has no stored water. Does this mean it is low risk?

No. Having no stored water does lower the risk, but there are many factors to consider when identifying the Legionella risks. Is the pipe work insulated? Is the pipe work free from scale, corrosion and dead legs? Is the shower in good condition and free from scale? Are all the taps used regularly? Is the hot water system operating at the right temperature? Are the tenants over 45, do they smoke, are they in good health?

I am a private landlord; how often do I need to have a Legionella Risk Assessment undertaken? How long is it valid?

A legionella risk assessment on a residential property can be valid forever. As long as it is reviewed regularly to ensure there are no changes to the water system and the correct information is passed onto the tenant you may only require a one off Legionella Risk Assessment.

I am a private landlord, what if I don't have a Legionella Risk Assessment undertaken?

You are running a serious risk.

If one of your tenants develops Legionnaires' Disease as a consequence of the water system in your property and you have not assessed the Legionella risks or informed the tenant of those risk, it may be classed as a breach of Health and Safety Law. You are legally responsible and the fines are unlimited. Why run the risk?

As a landlord, what are my duties?

Organisations, or self-employed individuals, who provide residential accommodation or who are responsible for the water system(s) in their premises, are responsible for ensuring that the risk of exposure to legionella in those premises is properly assessed and controlled. All water systems require an assessment of the risk. If you feel you are unable to do this yourself your must employ somebody who is competent to do so.

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