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Legionella Management
Introduction
Legionnaires’ disease is potentially fatal, with bacteria common in natural water sources, and may
also contaminate purpose-built water systems such as cooling towers, evaporative condensers, and
hot and cold water systems. Anyone can develop Legionnaires’ disease, but the elderly, smokers,
alcoholics and those with cancer, diabetes or chronic respiratory or kidney disease are most at risk.
HSE’s Legionnaires’ disease page provides information on managing the risks
There is potential for Legionella to be present in your water system if:
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Water is stored or re-circulated in your system
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The water temperature in all or part of your system is between 20–45 °C;
this is because the bacteria multiply where temperatures are between 20-45°C and nutrients
are available, and the bacteria are dormant below 20°C and do not survive above 60°C
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There are sources of nutrients such as rust, sludge, scale and organic matters
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The conditions are likely to encourage bacteria to multiply
Duties
The person in control of premises has health and safety duties, and needs to take suitable precautions
to prevent or control the risk of exposure to Legionella.
Details can be found in part 1 of Legionnaires’ Disease: The Control of Legionella Bacteria in Water
Systems, guidance and code of practice.
Risk Assessment
Carrying out a risk assessment will help you to identify potential risks and implement measures to
either eliminate or control them. 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. Where you
choose to use an external organisation you need to be certain that they are competent to proceed
with the assessment. It is not always necessary to carry out a water test.
The competent person needs to understand your water system and any associated equipment, and
should establish any possible risk of exposure to Legionella.
Your risk assessment should include:
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the name and responsibilities of the competent person
system description
potential risk source
controls currently in place to control risks
monitoring, inspection and maintenance procedures
records of the monitoring results, inspection and checks carried out
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. Key system changes
should also prompt a review.
Competent Person
As an employer or person in control of premises, you must appoint someone competent to help you,
i.e. 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.
This can be someone internal or external, or a combination of the two.
If you decide to employ contractors to carry out assessments or other work, it is still the responsibility
of the competent person to ensure that the assessments or work is carried out to the required
standard. It is the duty holder’s responsibility to ensure that persons employed to assess or manage
the risk are fully competent to do so.
You must identify ‘sentinel’ outlets (those furthest and closest to each tank or cylinder) for monthly
checking of the distribution temperatures. You should also check the hot water storage cylinder
temperatures every month and cold water tank temperatures at least every six months.
Stagnant water favours Legionella growth. To reduce the risk you should remove dead legs/dead ends
in pipe-work, flush out infrequently used outlets (including showerheads and taps) at least weekly,
and clean and de-scale shower heads and hoses at least quarterly. Cold-water storage tanks should be
cleaned periodically and water should be drained from hot water cylinders to check for debris or signs
of corrosion.
Temperature Control
The primary method used to control the risk from Legionella is water temperature control.
Water services should be operated at temperatures that prevent Legionella growth:
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Hot water storage cylinders (calorifiers) should store water at 60°C or higher
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Hot water should be distributed at 50°C or higher (thermostatic mixer valves need to be fitted
as close as possible to outlets, where a scald risk is identified)
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Cold water should be stored and distributed below 20°C
Records
The following should be recorded:
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Significant findings, including any groups of employees identified as being particularly at risk
Steps taken to prevent or control risks
Names of the person responsible for risk assessment
A written control scheme and details of implementation
The dates and results of any inspection, test or check carried out
This should include details about the state of operation of each system, e.g. 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.
Responsibilities and Contact Details
Duty Holder (Practice, landlord etc.)
Competent person
Company / address
Additional controls
Water samples should be analysed for Legionella periodically to demonstrate that bacteria counts are
acceptable. The frequency should be determined by level of risk, in accordance with the risk assessment.
Other control methods
Other methods to control Legionella include copper and silver ionisation and biocide treatments (eg chlorine
dioxide). To ensure that they remain effective their application will need suitable assessment as part of the
overall water treatment programme, including proper installation, maintenance and monitoring.
Further information
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Hot and cold water systems
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HSE Website – Legionnaires’ disease - provides guidance on managing the risks
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Approved Code of Practice (ACoP) (L8 Rev 3) Legionnaires’ disease: The control of Legionella bacteria in
water systems - sets out both established standards for managing the risks from Legionella and provides
guidance on how to comply with the law.
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HSG220 - Health and safety in care homes - provides guidance on how to manage the risks at care homes
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HPA Website – Legionnaires’ disease
- provides information on Legionnaires’ disease and the requirement
to report cases in England and Wales to the Health Protection Agency
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HPS Scotland – Legionnaires’ disease
– provides information on Legionnaires’ disease and the
requirement to report cases in Scotland to HPS