LEGIONNAIRES DISEASE 
RISK ASSESSMENT 

Legionnaires Disease risk assessment & guidelines 

 
Who can carry out an assessment? 
 
Landlords and letting agents can carry out a Legionnaire’s risk assessment themselves if the property is a single dwelling or a flat with its own water supply (hot and cold) and they are competent to do so. In particular landlords should: 
 
understand different types of water systems 
 
understand Legionella bacteria and the factors which increase the risk of an outbreak in a 
domestic setting 
 
understand the control measures which if present will reduce the risk of an outbreak within a 
domestic setting 
 
Before considering carrying out a risk assessment you should familiarise yourself in particular with the following HSE publications: - 
Legionnaire’s disease:  
 
A brief guide for duty-holders - http://www.hse.gov.uk/pubns/indg458.pdf  
 
Legionnaire’s disease Part 2: The control the relevant part of Legionella in hot and cold water systems - http://www.hse.gov.uk/pubns/indg458.pdf 
 
If you do not consider that you are competent then give the task to someone who is. 
 
The risk assessment process 
The practical risk assessment should include a site survey of the water system. A template is attached which is suitable for a basic system and can be adapted as required. The assessor should complete all the relevant sections. 
 
The assessor should understand the water systems and any associated equipment in the property, in order to conclude whether the system is likely to create a risk from exposure to Legionella. 
 
It is important to identify whether: 
 
water is stored or re-circulated as part of the system (particular areas of risk include water tanks, dead legs, shower heads and/or long runs of pipe work containing warm water) 
 
the water temperature in some or all parts of the system is between 20 – 45°C (hot water should be stored in any tanks at 60°C) 
 
if there are sources of nutrients such as rust, sludge, scale and organic matters 
 
conditions are present to encourage bacteria to multiply 
 
it is possible for water droplets to be produced and, if so, whether they could be dispersed, e.g. showers 
 
there are parts of the system that are used infrequently e.g. guest bathrooms 
 
it is likely that any of the tenants, residents, visitors etc are more susceptible to infection due to age, health or lifestyle and whether they could be exposed to any contaminated water droplets 
 
Reviewing the risk assessment 
If the risk assessment concludes there is no reasonably foreseeable risk or the risks are insignificant and are managed properly to comply with the law, the 
assessment is complete. Although no further action may be required at this stage, existing controls must be maintained. The assessment of risk is an ongoing process and not merely a paper exercise. The assessment should be reviewed regularly and specifically when there is reason to suspect it is no longer valid. 
Educating tenants Landlords should inform tenants of the potential risk of exposure to Legionnaire’s disease within domestic properties and its consequences. They should advise on any actions arising from the findings of the risk assessment, where appropriate. 
 
Tenants should be advised in particular that they should: 
 
inform the landlord/letting agent if they believe the hot water temperature is below 50°C or the hot water tank/boiler is defective in any way 
 
not adjust the temperature of the hot water 
 
advise landlord/letting agent if they believe the cold water temperature is above 20°C 
 
flush through little used outlets for 2 minutes at least once a week 
 
clean, disinfect and descale shower heads at least once every 6 months 
 
notify the landlord/letting agent if they notice any debris or discolouration in the hot or cold water 
Domestic hot and cold water systems can provide an environment where Legionella bacteria can grow. This can cause Legionnaires’ Disease which is a potentially fatal form of pneumonia caused by inhalation of small droplets of contaminated water containing Legionella bacteria. 
 
This advice sheet gives tips for residents of rented domestic accommodation such as houses, bungalows and flats in small blocks. 
 
In particular, it is important that you 
 
Do not interfere with the settings on your boiler or hot water system. The Hot Water should be set so that the water is heated up to 60°C. 
 
Tell your landlord if: 
 
 The cold water is still running warm after you have initially run off any water which may have accumulated in the pipes. It should not be above 20°C. 
  
There are any problems, debris or discolouration in the water. 
  
The boiler or hot water tank are not working properly, particularly if the water is not coming out of the taps at a sufficiently high temperature. It should come out at a temperature of 50°C after it has run for a minute at the latest. 
 
Where showers are fitted  
 
If they are used only occasionally then flush them through by running them for at least two minutes every week. Keep out of the way whilst this is being done as far as possible. 
 
Clean the shower head periodically, descale and disinfect it. This should be done at least every six months. 
 
Where a property is left vacant for any time, e.g. student accommodation over the summer holidays, make sure that when it is occupied again at the outset both hot and cold water systems are flushed through by running all outlets for at least 2 minutes. 
 
Legally, it is your landlord’s responsibility to take precautions to prevent Legionella being present in the hot or cold water system but tenants and residents also have an important part to play in taking these simple and practical precautions. 

 Legionnaires Disease Risk Assessment  Order by e-mailing info@HelpMeRent.co.uk OR complete this on-line form, we charge £10 to send you a PDF Version  

Legionnaires Disease Risk Assessment Form 

Risk Categories  1. Water outlet temperature 

Cold water must flow from outlets at below 20°C and hot water above 50°C to minimise risk. If temperatures are too low/high then adjustments need to be made to the system such as lagging of pipework or adjustment of temperature settings for hot water. 
 
Identify any defect/risks and related recommendations associated with water outlet temperature. If any action is required identify responsible person 

2. Cold water storage tanks 

If any debris etc. is present in the system it should be drained and thoroughly cleaned. If debris is from corrosion on the tank itself then the tank may need to be replaced. All cold water tanks should have tight fitting lids to prevent debris entering the system. 
 
The water in the tank should be below 20°C and the tank should be insulated to prevent the temperature rising above this level 
Identify any defect/risk and related recommendations associated with cold water storage. If any action is required identify responsible person 

3. Hot water 

If the temperature is set at above 60°C this can cause scalding to users. 
The temperature setting on the boiler and/or hot water tank should be set and maintained at 60°C. 
Identify any defect/risk and related recommendations associated with hot water. If any action is required identify responsible person 

4. Shower heads 

All shower heads should be cleaned, disinfected and descaled at least once every 6 months. Aerosol production should be minimised during this process. 
Identify any risks and related recommendations associated with shower heads. If any action is required identify responsible person 

5. Unoccupied properties 

During periods of unoccupancy all outlets on hot and cold water systems should be flushed through at least once a week for at least 2 minutes. For long periods consider draining the system. 
 
Make sure that the system is flushed through when it is re-occupied by running all outlets for at least 2 minutes. Aerosol production should be minimised during this process 
Identify any risks and related recommendations associated with unoccupancy. If any action is required identify responsible person 

6. Advice to tenants 

This can be done by giving the tenant/s the tenant advice sheet. 
 
The assessment is complete and should be reviewed regularly (at least once a year) and specifically when there is reason to suspect it is no longer valid. You should ensure that the recommendations above are implemented and any existing controls maintained. 
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