Practical Guidance And Template For Legionella Risk Assessment


This page provides practical guidance on your risk assessment for controlling Legionellosis bacteria.

We recommend using our specially designed iAuditor template for iOS or Android devices, which requires downloading a free app and then our template. 

It is swift and intuitive to use and will save considerable time. The app only works on iOS or Android devices, but you can export the reports onto a desktop computer in many formats (including PDF and Word). 

Moreover, Safetyculture (who makes the iAuditor app) offers a service where templates and audits can be synchronised between iOS and Android devices. This may require a separate subscription to our template.

You may use the template on up to 10 devices you or your company own under the licence.

Not a member of the Guild?

The template, forms and guidance are free to subscribers of the Guild. However, if you're not a member of the Guild, it's not a problem! 

You can purchase our "legionella pack", which costs £19.00 and includes 12 months of free updates plus 12 months of full access to this guidance page. The legionella pack includes:

  • Legionella risk assessment template for the iAuditor app
  • Paper legionella risk assessment form
  • Paper legionella risk assessment checklist
  • Tenants' information leaflet about controlling legionella
  • Full access to this legionella risk assessment guidance page (for 12 months)
  • Use the template on up to 10 devices owned by you or your company

You can access all these files from here. 

Remember, you need to install the iAuditor app first, so please download that before purchasing to check if the template will work on your device (if you can get iAuditor working, our template will work).

Refund policy

We offer a full 30-day no-quibble refund if you are not entirely satisfied with our template (only available to purchases of the template by non-subscribers of the Guild as the template is included for free with a Guild subscription).

Download the risk assessment template.

To see the latest version and a history of changes made, please see the product page for the template.

Step 1 - download the free iAuditor app onto your device

Step 2 - Only once step 1 has been done (otherwise, the template won't be recognised), download our template* using the device you have installed the app on and the default browser (e.g. Safari on iOS). 

When prompted, select "open in iAuditor". Alternatively, you could download it to a desktop, email it to the device iAuditor is installed on, and open it in the default email client (e.g. Mail in iOS). Install on up to 10 devices owned by you or your company.

*Important: the free iAuditor app has a public directory of templates, and by downloading ours, you agree NOT to put our template in the public directory.

The advantage of using the iAuditor app is that it can publish remarkably professional-looking reports, record your audits, remind you of any reviews, and there are in-app purchases available (not required for our template) to enhance the usage of the app further.


You can see a sample Legionella risk assessment report from the iAuditor template.

We have also produced a simple-to-use paper legionella checklist, which is handy if you ask your plumber to gather specific basic information about the installation.

Finally, a paper version of a legionella risk assessment is available for download here. This also includes a simple checklist.

At the bottom of this page is a video showing a live risk assessment and the app.

Legionnaires' disease

Legionellosis is a collective term for diseases caused by legionella bacteria, including the most serious legionnaires' disease and the similar but less severe conditions of Pontiac and Lochgoilhead fever. Legionnaires' disease is a potentially fatal form of pneumonia, and everyone is susceptible to infection. The risk increases with age, but some people are at higher risk, e.g. people over 45, smokers and heavy drinkers, people suffering from chronic respiratory or kidney disease, diabetes, lung and heart disease or anyone with an impaired immune system.

Legionella pneumophila and related bacteria are common in natural water sources such as rivers, lakes and reservoirs. They may also be found in purpose-built water systems, such as hot and cold water systems and spa pools. 

If conditions are favourable, the bacteria may multiply, increasing the risks of legionnaires' disease, and it is essential to control the risks by introducing appropriate measures. 

Legionnaires' disease is typically contracted by inhaling tiny droplets of water (aerosols) suspended in the air containing the bacteria, so showers and spa baths are at higher risk. 

There is no risk from drinking contaminated water.

The need for a risk assessment

After a change to the Approved code of practice and guidance (ACOP), it became more of a requirement for landlords when the scope included smaller water systems and storage tanks of less than 300l.

The guidance states:  

All systems require a risk assessment, however not all systems will require elaborate control measures. A simple risk assessment may show that the risks are low and being properly managed to comply with the law. In such cases, you may not need to take further action, but it is important to review your assessment regularly in case of any changes in your system, and specifically if there is reason to suspect it is no longer valid.

The Law

Various laws govern the requirement for a landlord or agent to complete a risk assessment, namely:

Heath and Safety at Work etc. Act 1974

Section 2(1) would typically cover agents as it requires all employers to ensure reasonably practicable the health and safety of all employees. 

Section 3(1) continues to require that employers or self-employed persons (which will include landlords) must ensure all persons not in their employment are not exposed to risks to their health and safety.  

Control of Substances Hazardous to Health Regulations 2002 (COSHH)

Regulation 6 of the COSHH provides employers and self-employed persons (agents and landlords in this context) shall not carry out work that is liable to expose any person to any substance hazardous to health unless a suitable and sufficient assessment of the risk has been made.

Approved Code of Practice and Technical Guidance - L8

The ACOP and accompanying technical guidance make it clear that legionella is a hazardous substance for the COSHH regulations and provides advice which will assist with creating a suitable and sufficient risk assessment (risk assessment for short).

This Guidance

Here we provide some practical guidance and a form for producing a Legionella risk assessment. The advice and form are suitable for a low-risk domestic property with either a combination boiler or basic water storage for hot water used daily.

It should be noted from the outset that although you must do a risk assessment in all cases, it is not required to be recorded in writing where there are less than five employees. However, the ACOP guidance recommends recording all risk assessments, even those that do not need them. 

Who should carry out the risk assessment?

The ACOP requires a "competent person" to assess the risk. Where risks are small, as defined above, there is no reason why a landlord or small agent cannot do the assessment themselves. Where there are five or more employees or if you don't feel confident, the employment of a specialist may be more appropriate.

The 'duty holder' will have the general duty to ensure the property is safe and to carry out the risk assessment (if they are competent). Or, the duty holder can arrange for a professional to evaluate them. Usually, the duty holder will be the landlord but could also be the letting agent.

Once a duty holder has been identified, that person can nominate a "responsible person" who will undertake any general routine duties found under the risk assessment. Commonly the duty holder will appoint themselves as the responsible person.

It is perfectly acceptable for the duty holder to ask a competent person such as a gas engineer when next carrying out a gas safety check to look for specific risks such as tanks in the loft, dead legs and checking temperatures. We have provided a simple checklist which you could ask your plumber to complete as much or as little as you request. The information gathered from the checklist can be easily transposed onto the iAuditor template and quickly produce a comprehensive risk assessment.

Identifying the risk

The risk assessment should identify and evaluate potential sources of risk and:

  • The particular means of preventing exposure to legionella bacteria;
  • Or if prevention is not reasonably practicable, the particular means of controlling the risk from exposure to legionella bacteria.

Several factors create a risk of someone acquiring legionellosis, such as:

  • The presence of legionella bacteria;
  • conditions suitable for the growth of the organisms, e.g. proper water temperature (20 °C–45 °C) and deposits that are a source of nutrients for the organism, such as sludge, scale, rust, algae, other organic matter and biofilms;
  • a means of creating and spreading breathable droplets, e.g. the aerosol generated by showers or spa pools;

The following list contains some of the factors to consider in a simple residential property, as appropriate, when carrying out the risk assessment:

  • Where it is mains into the building, this is ordinarily low risk. However, some farms have their water supply, so they must ensure bacteria cannot enter the supply before entering the cold water storage tank (if one).
  • If a combination boiler is used, risks are lowered because there is little water storage.
  • Where there is a water tank, the risks are increased if tanks are not clean, not insulated or don't have a well-fitted lid and should be put on the assessment.
  • Hot water cylinders increase the risk, especially when left unheated during void periods. Of exceptionally high risk are fortic tanks because the hot water below will heat the supposedly cold tank directly (and attached) above. This can result in ideal temperatures for legionella growth.
  • Look for dead legs (a water pipe capped off). If there are any, they should be recorded, as their stale water can be a source of multiplication at the correct temperatures.
  • What temperature is the hot water set on the boiler and cylinder? (Legionella breeds at between 20 and 45 degrees)
  • What are the temperatures of the water from the outlets? We believe you can complete no risk assessment successfully without measuring these temperatures. A simple thermometer probe should be sufficient for a small landlord or agent, but a more professional thermometer will be more appropriate if doing more.

Preventing and controlling the risk

The following list will assist with recording the risk assessment recommendations for preventing and controlling legionella:

Water storage

  • If a water tank is present, this should be recorded. Tanks should have a well-fitted lid to prevent contamination. They should be clean inside and lagged to avoid heating above 20 degrees in summer. The tank's water temperature should be recorded on the assessment. Take care when inspecting lofts.
  • Fortic tanks pose a higher risk and should be recommended to be removed at the earliest available opportunity (where proportionate).

Dead legs

  • If there are dead legs (pipes capped off), these should be noted and removed. The stale water within the dead leg can assist the breeding of legionella, and as the bacteria has a tail, it can swim out and into the water system.


  • What is the temperature of the hot water set? Legionella breeds at between 20 and 45 degrees, so ideally, you should set the temperature on the cylinder or combination boiler at 60 degrees (but no more than 60 for fear of scalding)
  • The temperatures from the cold water taps should be recorded on the assessment and be below 20 degrees, and legionella does not multiply below this temperature. Include all outlets, for example, outside taps and unused utility rooms.
  • The temperatures from hot outlets should be recorded on the assessment and be above 50 degrees, and this temperature kills the legionellosis bacteria. The temperature should not exceed 60 degrees for fear of scalding (around 55 is about perfect).
  • Hot tip: testing showers is difficult because the spray produces inaccurate results. Take the head off the shower and then test the water temperature. You will save lots of time! 
  • Hot tip 2: when checking temperatures from a combination boiler, you may find the hot is below 50 degrees. This might be because the flow rate of the cold going into the boiler is too fast, which means it's going through the boiler too quickly to heat up to temperature. In this case, ask your plumber to turn down the flow rate on the cold inlet until you can achieve 50 degrees when the tap is turned on fully.

Tenants information

  • Are there outside taps or unused rooms with taps? You should advise the tenant to run unused outlets at least weekly.
  • Do the tenants go away for extended periods? If so, they need to be advised if out longer than a week to heat the hot water to 60 degrees for one hour and then run the water through for 5 minutes. When away for a period, tenants should be advised to put the shower head in the bath before running.
  • Showers are the highest risk because the droplets can become stagnant in the head and cause a spray. The mist inhalation infects people (you can't become infected by drinking contaminated water). As a result, shower heads should be dismantled, disinfected and cleaned thoroughly at least quarterly or as indicated by the fouling rate.
  • Tenants can be given a leaflet explaining these recommendations at the time of the assessment if not already done. Then all new tenants should be given an information leaflet, and providing such information is sufficient for the ACOP guidance.

Spa pools

  • Spa pools, whirlpool baths, spa baths or hot tubs should ideally be removed as they pose the highest risk due to their operating temperatures and spray produced. The occupiers must be advised to disinfect after every use.

Void periods

  • During void periods, outlets should be run at least weekly during viewings. If the property is empty for longer than six weeks, the hot water should be heated to at least 60 degrees for one hour, and then all hot outlets run through for at least 5 minutes. The cold water should be run through for 5 minutes. For longer than six weeks, consideration should be given to having the system professionally cleaned.

Change of tenancy

  • At a change of tenancy, the void period guidance should be followed. You should check the temperatures on the boiler and hot water cylinder (if one) to ensure the previous occupiers didn't turn the temperatures down. There is no need to do another risk assessment at each changeover of tenants as long as the temperatures are checked, and there is no other reason to suspect something has changed since the last evaluation.

Recording the risk

you should enter all of the above and anything else referenced in the ACOP guidance onto the risk assessment form, along with any remedial action recommended and taken. For example, the risk assessment could identify a loft's water tank with no lid. This is an increased risk, and the appraisal should recommend a cover be fitted. You can further update the evaluation once the top has been done, thus reducing the risk.

We produce a template for an app that can be downloaded, allowing for easy recording and monitoring of risks found (see at the top of this page).

The ACOP guidance provides:  

Once the risk has been identified and assessed, a written scheme should be prepared for preventing or controlling it. In particular, the written scheme should contain the information about the water system needed to control the risk from exposure. However, if it is decided that the risks are insignificant and are being properly managed to comply with the law, you may not need to take any further action. But it is important to review the risk assessment regularly and specifically if there is reason to suspect it is no longer valid, for example changes in the water system or its use.

Reviewing the risk assessment

You should review the risk assessment regularly (recommended at least every two years) and whenever there is reason to suspect that it is no longer valid, for example, if there is:

  • a change to the water system or its use;
  • a change to the use of the building where the system is installed;
  • new information available about risks or control measures;
  • the results of checks indicating that control measures are no longer effective;
  • changes to key personnel;
  • a case of legionnaires' disease/legionellosis associated with the system.

View Related Handbook Page

Controlling Legionellosis

Legionellosis is a collective term for diseases caused by legionella bacteria including the most serious, Legionnaires’ Disease