Overview
As an employer, or someone in control of premises (including landlords), you are responsible for health and safety and need to take the right precautions to reduce the risks of exposure to legionella. You must:
identify and assess sources of risk
manage any risks
prevent or control any risks
keep and maintain the correct records
carry out any other duties you may have
To help you understand the risks, the HSE has produced guidance on what Legionnaires' disease is. This explains the causes of the disease and its symptoms.
Relevant legislation
Duties under the Health and Safety at Work etc Act (HSWA) extend to risks from legionella bacteria, which may arise from work activities.
The Management of Health and Safety at Work Regulations (MHSWR) provide a broad framework for controlling health and safety at work.
More specifically, the Control of Substances Hazardous to Health Regulations (COSHH) provide a framework of actions designed to assess, prevent or control the risk from bacteria like legionella and take suitable precautions.
The Approved Code of Practice Legionnaires' disease: the control of legionella bacteria in water systems (L8) contains practical guidance on how to manage and control the risks in your system.
Identify and assess sources of risk
Carrying out a risk assessment is your responsibility. You may be competent to carry out the assessment yourself but, if not, you should call on help and advice from a competent person, either within your own organisation or from outside sources, for example consultancies.
A competent person is someone who has sufficient training and experience or knowledge and other qualities that allow them to assist you properly. HSE has more guidance on how to appoint a competent person.
What to look for in your water system
You, or the person responsible for managing risks, need to understand your water systems, the equipment associated with the system such as pumps, heat exchangers, showers etc, and its constituent parts.
Identify whether they are likely to create a risk from exposure to legionella, and whether:
the water temperature in all or some parts of the system is between 20–45°C
water is stored or recirculated as part of your system
there are sources of nutrients such as rust, sludge, scale, organic matter and biofilms
the conditions are likely to encourage bacteria to multiply
it is possible for water droplets to be produced and, if so, whether they can be dispersed over a wide area, for example showers and aerosols from cooling towers
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.
Specific systems likely to cause risk
You will also need to consider technical and further information on the following systems:
What to include in your risk assessment
Your risk assessment should include:
management responsibilities, including the name of the competent person and a description of your system
competence and training of key personnel
any identified potential risk sources
any means of preventing the risk or controls in place to control risks
monitoring, inspection and maintenance procedures
records of the monitoring results and inspection and checks carried out
arrangements to review the risk assessment regularly, particularly when there is reason to suspect it is no longer valid
If you conclude that there is no reasonably foreseeable risk or the risks are low and are being properly managed to comply with the law, your assessment is complete.
You may not need to take any further action at this stage, but any existing controls must be maintained and the assessment reviewed regularly in case anything changes in your system.
Managing the risk
As an employer, or person in control of premises, you must appoint someone competent to help you meet your health and safety duties and to take responsibility for controlling any identified risk from exposure to legionella bacteria.
A competent person, often known as the responsible person, is someone with sufficient authority, competence, necessary skills, knowledge of the system, and experience. The appointed responsible person could be one, or a combination of:
yourself
one or more workers
someone from outside your business
If there are several people responsible for managing risks, for example because of shift-work patterns, you must make sure everyone knows what they are responsible for and how they fit into the overall risk management of the system.
Using contractors to carry out water treatment
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 the treatment is carried out to the required standards.
Before you employ a contractor, you should be satisfied they can do the work you want to the standard you require.
There are a number of external schemes to help you with this, for example, A Code of Conduct for service providers.
The British Standards Institute have published a standard for legionella risk assessment.
Preventing or controlling the risk
You should first consider whether you can prevent the risk of legionella by looking at the type of water system you need. For example, identify 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 and multiplication of legionella.
Cleaning and disinfecting your 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. This will take account of factors such as:
whether the system is open or closed
the type and level of contamination
the people that could be exposed
Cleaning a cooling tower pack
When you can easily remove a cooling tower pack and reinstate it safely without damage, this will help you inspect it and assess the need for cleaning. However, you should consider the tower’s construction and the possibility of removing it when deciding how to clean and maintain the water system.
Whether the pack is removed or not, you should:
demonstrate evidence of its cleanliness
make an assessment using appropriate techniques
record any findings recorded
You can find more guidance on cooling tower packs in Part 1 of Legionnaires' disease: Technical guidance.
Describing the controls you need
If you identify a risk that you are unable to prevent, you must introduce a course of action. This is called a ‘written control scheme’ and it will help you manage the risk from legionella and implement effective control measures, by describing:
your system, for example by developing a schematic diagram
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
what checks will be carried out, and how often will they be carried out, to ensure the controls remain effective
You should:
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 removing redundant pipework
avoid materials that encourage the growth of legionella (the Water Fittings and Materials Directory 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
treat water to either control the growth of legionella (and other microorganisms) or limit their ability to grow
monitor any control measures applied
keep records of these and other actions taken, such as maintenance or repair work.
Monitoring and keeping records
If you have 5 or more employees you have to record any significant findings, including those identified as being particularly at risk and the steps taken to prevent or control risks.
If you have fewer than 5 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 of the:
person or people responsible for conducting the risk assessment, managing, and implementing the written scheme
significant findings of the risk assessment
written control scheme and details of its implementation
details of the state of operation of the system (in use/not in use)
results of any monitoring inspection, test or check carried out, and the dates
These records should be retained throughout the period for which they remain current and for at least 2 years after that period.
Records kept in accordance with the results of any monitoring inspection should be retained for at least 5 years.
Remote temperature/flow monitoring
Legionella can grow in water systems between 20°C and 45°C, especially where there is a risk of stagnation. Avoiding this temperature range in a hot and cold-water system for as long as possible is a key control measure for reducing the risk of legionella bacteria growth in the system.
Traditionally, water temperature is periodically checked manually at outlets or on the surface of pipework to give some reassurance that the system is performing as it should. You can find guidance in hot and cold water systems - things to consider.
Remote monitoring systems can be used to monitor a hot and cold-water system. Part 2 of Legionnaires' disease: Technical guidance advises that automated monitoring programmes are increasingly used, and they allow for early detection of control regime failures. It is recommended that their implementation and use has been based upon a specific legionella risk assessment and agreed by a competent person.
Remote monitoring systems use temperature sensors to check the temperature of your water system at more frequent intervals, without having to physically visit the system. They normally consist of sensors attached to or inserted into water pipes which can measure the temperature, of either the water directly or indirectly through the pipe temperature. These sensors will send temperature readings back to a processing unit which will then present the data for review.
Most remote temperature monitoring systems can also provide some information on outlet usage. The remote monitoring system may achieve this by detecting changes in temperature as the water moves through the pipe when an outlet is used. This flow data can sometimes be helpful in the identification of and, when assessing the risk posed by, infrequently used outlets.
There is Water Management Society guidance on remote monitoring systems which provides more details on considerations to be made if you are considering implementing such a system.
Reviewing what you do
Checking what you do and reviewing your risk assessment regularly allows you to assess your performance before an accident, incident or case of ill health can happen.
This includes checking that you have been successful with your specific plans and objectives, the operation of your health and safety management system, and compliance with performance standards.
For example, with hot water outlets the water temperature should be at least 50°C (55°C for healthcare premises like hospitals) within 1 minute of running the water. This will help you implement improvements in the future.
You can find further information:
Questions to help you decide if your controls are working
The following general questions will help you to decide whether your approach to controlling legionella is working or whether it needs updating.
Is there a risk assessment in place for the system?
Does the risk assessment contain a description of your system, for example an up-to-date schematic diagram, showing the whole system including parts out of use?
Does the risk assessment conclude that there is no significant risk?
If the risk assessment does identify a significant risk
Is there a written control scheme in place to address the risks?
Has a responsible person(s) been identified in writing?
Are the roles and responsibilities of all staff involved in the control regime clearly defined in writing and have they all received appropriate training?
If external contractors are used
Are their roles and responsibilities clearly defined, in writing?
Have you checked on the competence of the contractors/consultants and found it acceptable (for example experience and qualifications, training, membership of professional organisations or recognised trade body)?
Other health and safety issues
Have you carried out COSHH assessments for handling of water treatment chemicals, working at height, working in confined spaces, electrical safety and ease of access to parts of the system?
Specific systems or services
Depending on your system, there are specific things you will need to monitor.
The frequency of inspection and maintenance will depend on the system and the risks it presents. All the inspections and measurements should be recorded.
Further technical guidance
You can find further information in Legionnaires' disease - Technical guidance. The publication covers the following systems, and it includes summary checklist tables for inspection frequency:
Part 1: The control of legionella bacteria in evaporative cooling systems
Part 2: The control of legionella bacteria in hot and cold water systems
Part 3: The control of legionella bacteria in other risk systems
There is also specific information and guidance on spa pools.
Duties under other regulations
Reporting cases of legionellosis
Under the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations (RIDDOR), you must report any cases of legionellosis in an employee who has worked on cooling towers or hot and cold water systems that are likely to be contaminated with legionella.
Notification of cooling towers or evaporative condensers
Under the Notification of Cooling Towers and Evaporative Condensers Regulations(NCTEC), 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 or when such devices are no longer in use.
Notification forms are available from your local authority or environmental health department.
Dry/wet coolers or condensers
Dry/wet coolers or condensers do not rely solely on the principle of evaporation, so these systems may not require notification under NCTEC. However, it is important to assess the system against the notification requirements defined in NCTEC, for example where such systems spray water directly onto the surface of the heat exchanger.
Here you can find HSE guidance on dry/wet cooling systems.
To learn more, why not complete our Basic Legionella Management eLearning Course:
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