The Complete Guide to Legionella Management for Landlords and Businesses

Welcome to your complete guide to Legionella management for landlords, businesses, and anyone who manages property.

If you want to learn more about ensuring compliance and keeping people safe, you’ll enjoy this comprehensive guide that tells you everything you need to know.


Spread through water droplets, Legionella bacteria can cause severe health conditions, including the potentially-fatal Legionnaires’ disease.

According to duties listed under the Health and Safety at Work Act 1974 (HSWA), an employer, landlord or the person in control of a business or residential premises is responsible for taking the right precautions to reduce the risks of exposure to Legionella. There can be stiff penalties for businesses that do not take the required steps to mitigate the risks of Legionella infection.

Key Requirements Include:

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Monitoring your water temperature at regular intervals

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Flushing both hot and cold taps for two minutes

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Recording results and retaining them for five years

Execute regular Legionella risk assessments to ensure that you do not receive hefty fines or are held liable under the law. In this light, the most robust method of reducing risk is to install an automatic flushing and temperature testing system.


Legionnaires’ Disease

Legislation and Guidance

Legionella Risk Assessments

Legionella Testing

Industries at Risk

Automated Compliance System Benefits


Before we get into Legionella risk management, we’ll focus on why it is so important. In this chapter, we will answer the question: “What is Legionnaires’ disease?”

What is Legionnaires’ disease?

Legionnaires’ disease is a severe form of pneumonia caused by Legionella bacteria. The bacteria cause inflammation of the lungs. The condition can cause long term health problems, and even death.

When was Legionella discovered?

Legionnaires’ disease got its name from the first known outbreak of the condition, which occurred in Philadelphia, USA in 1976. An American Legion convention was held at the Bellevue-Stratford Hotel, with over 2,000 members of the Legion in attendance. Within a week of the end of the convention, five attendees had died, and six died a few weeks later, all with similar symptoms.


Contracting Legionnaires’ Disease

300 500

People in England and Wales get
the disease each year.

Legionnaires’ isn’t spread from person to person, but from the inhalation of contaminated droplets of water in the air which contains the Legionella bacteria.

In every instance of the disease, the affected person would have inhaled droplets of the contaminated water supply in mist or spray form.

How Legionnaires’ Is Spread

How is legionella spread - Smarter Technologies

Where Can Legionella Be Found?

Legionella bacteria can be found in natural water sources, and can also make its way into human-made water systems.

Can Legionella Survive Out Of Water?

Legionella bacteria can be found in natural water sources, and can also make its way into human-made water systems.

The Spread Of Legionella Bacteria

Low levels of Legionella are generally not a cause for concern, but if a water source becomes contaminated to unsafe levels, anyone who encounters that water source is placed at risk. Any system that produces a spray or mist (causing inhalation of water droplets) poses a risk.

Can You Get Legionella From Drinking Water?

Legionnaires’ disease is caused by inhaling infected droplets of water, so it can only develop in the respiratory system. Although it’s unlikely, you could potentially inhale infected drinking water if you cough or splutter while drinking it.

Can You Get Legionella From Air Conditioning?

You could only be exposed to Legionella via air-conditioning if your air conditioning uses a water-based system of cooling which then becomes infected with the Legionella bacteria or if the system has been contaminated from elsewhere in the building.

Who Is Most At Risk Of Catching Legionnaires’ Disease?

Most people who are exposed to Legionella do not become ill; some people are at greater risk of developing Legionnaires’ disease.

Risk Factors Include

AGED 50+





The Symptoms Of Legionnaires’ Disease

Early symptoms of the disease include:

  • Muscle aches
  • Tiredness
  • Headaches
  • Dry cough

These flu-like symptoms typically occur between two and ten days after exposure to Legionella bacteria.

As the disease progresses, other symptoms more indicative of pneumonia begin to appear:

  • Green phlegm
  • Shortness of breath
  • Chest pain
  • Confusion

How Legionnaires’ Disease Is Diagnosed

A chest x-ray will confirm if pneumonia is present. Samples of both urine and phlegm can be taken to test for the presence of the Legionella bacteria.

Is Legionnaires’ Disease Fatal?


Although the average mortality rate of Legionnaires’ is 10%, the mortality rate is dependent on the population infected. For example, outbreaks in hospitals or care homes may have a higher mortality rate since it will infect people who are elderly or already compromised.

Legionnaires’ Disease Treatment

Antibiotics are administered to kill the Legionella bacteria. Many people diagnosed with Legionnaires’ disease will go into hospital to be treated so that antibiotics can be delivered via a drip.

Depending on the severity of the condition and the diagnosis and treatment timelines, recovery may take several weeks or months. In serious cases, people have reported lasting effects such as fatigue, neurological symptoms, and neuromuscular conditions.


In the UK, if you are an employer or someone in control of premises (including landlords), it’s your legal obligation to understand the health risks associated with Legionella. It’s your responsibility to take the right precautions to reduce the risks of exposure to Legionella. You must understand how to:

  • identify and assess all sources of risk
  • manage these risks
  • prevent or control any risks
  • keep and maintain the correct records of assessment, testing and control
  • carry out any other duties you may have

The following legislation covers your legal duties for conducting a Legionella risk assessment:

Is Legionella Risk Assessment A Legal Requirement For Landlords?

All landlords must be able to prove they have assessed Legionella risk at their property and are controlling the identified risks to keep people safe.

Do Landlords Need A Legionella Risk Assessment?

If you are a landlord and rent out your property (including a room within your own home), you have legal responsibilities to ensure the health and safety of your tenant. This includes keeping the property free from health hazards, such as Legionella risks. Although there’s no official ‘Legionnaires’ control certificate’, conducting a risk assessment and taking steps to mitigate Legionella risks demonstrates your commitment to tenant health and safety.

Is Water Temperature Testing A Legal Requirement?

As discussed, water temperature testing itself is not a legal requirement, but it is your legal duty to control the risk of Legionella. Water temperature testing is one way of doing this.

Penalties For Not Carrying Out Legionella Risk Testing

Legionella compliance is governed by a number of different laws and regulations, which means that fiscal punishments received by guilty parties vary.

  • Minimum amounts cited by magistrates courts are in the region of £20,000.
  • There is also the threat of the guilty parties receiving a criminal record.
  • Those found culpable could even face a 12-month custodial sentence.

[READ MORE] About Legionella and the law

Should there be loss of life of victims of Legionnaires’ disease due to negligence, the Crown Prosecution Service can bring a prosecution under the Corporate Manslaughter and Corporate Homicide Act 2007. Under this legislation, penalties can be unlimited fines that run into millions of pounds, along with remedial orders and publicity orders.

That’s why it’s important for organisations, landlords and anyone in charge of a property to keep an up-to-date Legionella risk assessment and record of appropriate steps taken to control the bacteria.

[READ MORE] About fines for Legionella non-compliance

Actual Penalties Incurred For Legionella Non-compliance


2019 fine imposed on Bupa after the death of a care home resident with Legionnaires’ disease.


Isher Hangers failed to put suitable measures in place to control the risk of Legionella bacteria from the cooling tower on their premises.


Fine for shops leased out by Barrow Council in Cumbria for breaching health and safety laws.


It’s a legal requirement for all UK businesses (regardless of size) to conduct a Legionella risk assessment. It’s an important health and safety process intended to protect you, your business and anyone who comes into contact with your premises from harm. In this chapter, we discuss the Legionella risk assessment requirements and process.

What Is Involved In A Legionella Risk Assessment?

A Legionella risk assessment highlights potential dangers and the steps that should be taken to reduce levels of bacteria in a building or water system.

Even though there’s no official ‘Legionella test certificate’, landlords and those responsible for properties must be able to prove that the property’s Legionella risk has been assessed and that they are controlling the identified risks.

How To Carry Out A Legionella Risk Assessment:

As a landlord, building owner or manager, you need to assess the risk of Legionella bacteria multiplying in all water systems.

Identify Risk Factors

Although Legionnaires’ disease is considered to be preventable, any human-made water system may allow Legionella bacteria to grow under certain conditions:

  • 20°C – 45°C – Water temperature
  • Creates/ spreads – breathable droplets of water
  • Re-circulates – water
  • Stores – or contains nutrients for the bacteria to grow

You’ll need to pay particular attention to any system containing water in which Legionella could grow and be released in aerosol droplets:

Hot & cold water systems

Cooling water systems

Cooling towers

Evaporative condensers

Spa pools

Spray humidifiers



Vehicle wash systems


What A Risk Assessment Should Include

  • Management responsibilities – the name of the competent person and a description of your system
  • Competence and training of key personnel
  • Identified potential risk sources
  • Means of preventing the risk
  • Controls in place to control risks
  • Monitoring, inspection and maintenance procedures
  • Dated records of these procedures
  • Plans to review the risk assessment regularly

For Multiple Properties:

If your business has several premises, each must be risk assessed individually.

Who Can Carry Out A Risk Assessment?

As a business owner, building owner or property manager, or landlord, you can choose to carry out a Legionella risk assessment yourself if you have the appropriate skills and experience to complete the task correctly.

A competent person (known as the responsible person) is someone with sufficient competence, authority, experience the necessary skills and knowledge of the system.

The appointed responsible person/people could be:

  • yourself
  • one or more of your workers
  • someone from outside your business (such as a paid third-party service provider)

If there are several people responsible for managing Legionella risks, it’s essential to ensure that everyone knows their responsibilities and how they fit into the overall risk management strategy.

  • Don’t have the necessary training, experience and knowledge?

  • Is your site large or complex?

If so, your Legionella risk assessment is best left to a professional.

Can I Do My Own Risk Assessment?

If you own a small property that has a simple hot and cold water system, you may decide to conduct the Legionella risk assessment yourself.

In the majority of domestic cases, no special training is needed to conduct a Legionella risk assessment, as long as the person performing the assessment has competent knowledge of health and safety requirements.

How Long Is A Legionella Risk Assessment Valid For?

The risk assessment itself is not the end of your responsibilities, as risks can change, be introduced, or disappear. It all depends on your water system, how it’s used and whether or not it changes. You’ll need to review your risk assessment regularly to determine whether any such changes have occurred.

How Often Should A Legionella Risk Assessment Be Carried Out?


At a minimum, you should review your Legionella risk assessment at least every two years.


On sites with large and complex water systems (especially those with swimming pools, cooling towers and hot tubs), routine testing should be carried out at least once every three months.

How Much Does A Legionella Risk Assessment Cost?

The cost of your Legionella risk assessment will vary according to the size, quantity, and complexity of the buildings and water systems to be assessed. A straightforward project may cost as little as £250; a site with more complex requirements could cost £2,000 and upwards.

Legionella Compliance Records

Record keeping is important when assessing Legionella risks in the workplace. You are legally required to keep records of risk assessments and control measures to demonstrate compliance.

How Long Should Legionella Water Temperature Testing Records Be Kept?

According to UK law, all businesses with five or more employees must keep written records of water temperature testing dating back for five years.

These records should cover:

  • All Legionella risk assessments and reports
  • Significant findings of the risk assessment
  • Any actions taken to manage and control the risks
  • The person or persons responsible for conducting the risk assessment as well as managing and implementing the written scheme
  • Details of the state of operation of the water system
  • Results and dates of any monitoring inspection, test or check carried out

Even if your business has fewer than five employees, it’s still advisable to keep all records and assessments. This documentation provides evidence of all steps taken and is a useful document to refer to in future.

The Simplest Way To Keep A Record Of Legionella Compliance Testing

Using a smart, automated Legionella compliance system means that all data is saved and accessible on-demand in the cloud.


Legionella can multiply at an extremely fast rate, especially in stagnant water at the right temperature. That’s why regular flushing and monitoring of hot and cold water temperatures is crucial with regards to controlling Legionella growth in a water system.


Testing For Legionella Compliance

As with your Legionella risk assessment, a competent and qualified person within your organisation or a third-party specialist can test your water systems.

How To Test For Legionella In Water

The primary method used to control the risk from Legionella is water temperature control.

As discussed, you need to test the temperature of your water systems to avoid water reaching the right temperature for Legionella bacteria to proliferate (between the temperature range of 20°C and 45°C).

Legionella And Temperature

Legionella bacteria require specific temperature conditions to survive and multiply:

Legionella Thermometer - Smarter Technologies

Because Legionella only survive and multiply within a specific temperature range, keeping water temperatures below or above this can help mitigate the risks of Legionella infection.

Water Temperature To Prevent Legionella


Hot water storage cylinders (calorifiers)


Hot water distribution


Cold water storage and distribution

Check The Sentinel Outlet

The sentinel outlet is the tap that is located at the nearest and furthest point from the calorifier, water heater (for hot water) or the source (for cold water).

Sentinel outlet - Smarter Technologies

How To Carry Out Legionella Temperature Testing

There are two ways to carry out water temperature testing – manually taking the temperature at sentinel outlets at regular intervals, or installing a smart system that can take temperatures automatically at predefined intervals.

First, we’ll look at the more labour- and time-intensive manual testing.

Manual Legionella Control Testing

How To Check Your Hot Water Temperature To Control Legionella Risks

  1. Turn on the sentinel outlet for your hot water.
  2. Hold a thermometer under the running water for at least a minute.
  3. Ensure that the temperature reaches at least 50°C.
  4. Record the temperature.

If the temperature doesn’t reach 50°C within one minute, report it to the responsible person to take remedial action.

How To Check Your Cold Water Temperature To Control Legionella Risks

  1. Turn on the cold water sentinel outlet.
  2. Hold a thermometer under the running water for at least two minutes.
  3. Ensure that the temperature reaches below 20°C.
  4. Record the temperature.

If the temperature is not below 20°C within two minutes, report it to the responsible person to take remedial action.

How Long Should I Run Water To Prevent Legionella?

1 Minute

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2 Minutes

Cold tap - Smarter Technologies

How Often Should Legionella Temperature Testing Be Carried Out?

At the very least, testing should take place:


Sentinel outlets (furthest and closest to each tank or cylinder)


Hot water storage cylinders and cold water tanks

Truly effective monitoring for risk of Legionella requires constant, real-time water temperature checks. This is made possible through automated flushing and temperature checking.

Recommended Legionella Flushing Regimes


The minimisation of aerosol must be achieved by placing a plastic bag with a corner cut off, secured over the tap outlet.


Any little used taps should be flushed for a minimum of 2 minutes on a twice weekly basis (avoid splashing to minimise the creation of aerosol).


Any little used shower outlet must be flushed through for a minimum 2 minutes on a twice weekly basis.


Any little used appliances (E.g. Sluice Machines, Washing Machines etc.) should be flushed weekly (twice weekly for healthcare organisations).


Any little used toilet outlet should be flushed weekly (the lid should be in the down position to minimise aerosols).

How Much Does A Legionella Test Cost?

Testing can be expensive and inconvenient if it involves regular site visits by an expert.

Comparing Manual Legionella Control Testing To Automated Test And Flushing

Automated Legionella control testing and flushing saves significant time and resources. We’ll discuss automated systems further in Chapter 9.

This infographic compares manual Legionella control testing to automated testing, using the example of a building with two floors and four restrooms.

Legionella Infographic - Smarter Technologies

Checklist: Legionella Management Tasks

  • Carry out a Legionella and water safety risk assessment
  • Flush through little used outlets (deadlegs)
  • Check and record hot water storage vessel temperatures
  • Check and record sentinel temperatures
  • Dismantle, clean and disinfect shower heads and hoses
  • Check and record cold water storage cistern temperatures
  • Carry out cold water storage cistern inspections
  • Carry out inspections and purging of hot water storage vessels
  • Carry out inspections and purging of expansion vessels
  • Carry out servicing of expansion vessels
  • Check and record outlet temperatures (Over twelve months)
  • Carry out servicing of thermostatic mixer valves (TMV)
  • Carry out cistern clean and disinfections
  • Carry out Legionella sampling
  • Carry out TVC sampling

All individuals appointed should be properly trained to perform tasks in a safe and technically competent manner. Regular refresher training should be provided and records maintained.

Legionella Control By Design

Legionella growth favours stagnant water and a certain temperature range. To reduce the risk of bacteria growing, you should:

  • Remove dead legs/dead ends in pipe-work

  • Flush out infrequently used outlets (including showerheads and taps) at least weekly
  • Clean and descale shower heads and hoses at least quarterly.

  • Clean cold water storage tanks periodically

  • Ensure that the release of water spray (e.g. from cooling towers) is properly controlled

  • Drain water from hot water cylinders to check for debris or signs of corrosion.

  • Avoid water conditions and temperatures that favour the growth of Legionella and other microorganisms

  • Keep the system and water clean

Design Systems To Minimise Legionella Growth

  • Use only Water Regulations Advisory Scheme (WRAS) approved fittings, materials, and appliances

  • Keep pipe work as short and direct as possible to ensure water cannot stagnate anywhere

  • Insulate pipes and tanks

  • Use materials that do not encourage the growth of Legionella

  • Preventing contamination by fitting tanks with lids and insect screens


Any system that stores water could present a risk of Legionella. The most common sources of Legionella in human-made water systems include:

Cooling towers and evaporative condensers

Hot and cold water systems

Spa pools

Other assets at risk include:

Humidifier Icon - Smarter Technologies

Spray humidifiers

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Vehicle wash systems

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Sprinkler and hose reel systems

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Whirlpool baths

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Dental equipment

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Fountains and water features

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Foggers and water misting systems

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Air washers, wet scrubbers, particle and trivial gas scrubbers

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Emergency showers, eyebaths and face-wash fountains

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Horticultural misting systems

High, Medium, And Low Risk Of Legionella

Your approach to safely managing your water system depends on the level of risk present in that system.

Risk LevelHigh MediumLow
Risk factors
  • Cooling towers
  • Spas and hot tubs
  • Buildings with complex water systems
  • Hot and cold water systems
  • Process water systems
  • Simple water systems or no water at all
Building typesBuildings with vulnerable people present, such as hospitals and care homesLarger buildings such as hotels, offices, and factoriesRemote locations with minimal occupation and infection risk
Risk assessment frequencyRequire more frequent risk assessment to maintain control and safety.Every two years (unless there is a change to the water system and/or its usage.)Still need to be risk assessed to meet legal requirements.
Control measuresRegular testing and monitoring required, including checking water temperature levels.

All risk and control measures should be closely and consistently monitored.

Regular monitoring and testing of the water system and supply.Potentially no further steps need to be taken beyond periodically reviewing the risk assessment.

Healthcare Organisations

Why high risk? Healthcare facilities naturally include people who are at greater risk of developing Legionnaires’ disease.

  • Elderly
  • Infirm
  • Those with ongoing and complex medical conditions

In addition, buildings such as hospitals are also more likely to have large, complex hot and cold water systems.

Healthcare Icon - Smarter Technologies
Care Home Icon - Smarter Technologies

Care Homes

Why high risk? Like healthcare facilities, care homes are home to vulnerable populations and are likely to have large, complex hot and cold water systems.

Landlords And Property Managers

Landlords and property managers may manage anything from one property to multiple and complex properties and locations.

High-risk buildings include those with:

  • disused piping and equipment
  • storage tanks in multiple locations
  • taps and showers that are not often used
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Hospitality Icon - Smarter Technologies


Amenities such as showers, spa pools and hot tubs are high-risk locations for Legionella growth and contamination. These are widely found in hotels and other hospitality industry settings. Along with complex water systems, buildings like hotels can also have outlets that are intermittently used due to seasonal variations in demand. This increases the likelihood of water stagnation.

Manufacturing And Industry

Cooling towers and complex water processing systems are prevalent in manufacturing and industry. In addition, these sectors have large and complex facilities, making it even more challenging to prevent the spread of Legionella bacteria.

Water spray released from cooling towers can be unwittingly inhaled by workers in the immediate area. It can also travel on the wind and potentially affect others over a larger area. Tight controls are required for this reason.

Factory Icon - Smarter Technologies


Smarter Technologies offers pipe temperature sensors, wireless tank temperature sensors and automatic temperature testing and flushing units that are controlled via our smart building platform. This automated Legionella compliance system will ensure that your business stays compliant with guidelines on mitigating Legionella risks, as well as providing logs that are stored for five years.

The Benefits Of Automated Water Temperature Testing To Prevent Legionella

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Smarter Technologies’ Solution Consists Of:

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Automatic Flushing & Temperature Unit

This combination unit monitors temperatures and flushes the system according to your bespoke schedule, while simultaneously delivering real-time reports directly to your dashboard.

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Pipe Temperature Sensor

This sensor monitors hot and cold temperatures on the water pipes, sending you real-time alarm notifications if temperature thresholds do not meet the prescribed values. Both the unit and pipe sensors can be fitted to any sink, shower or designated tap using simple, ready-to-install industry standard fittings.

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Wireless Tank Temperature Sensor

This weighted, waterproof sensor is dropped into your water tank where it will continually monitor the temperature in real time, alerting you of any changes within the predefined parameters.

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