If you let a property or are in control of a residential building, health and safety law requires you to assess the risk of exposure to legionella bacteria from the water system and to put proportionate controls in place. The Health and Safety Executive (HSE) is clear that for most single homes this is a simple exercise that a landlord can usually carry out themselves.
The picture changes in larger buildings. A block with cold water storage tanks, hot water cylinders or calorifiers, booster pumps and long pipe runs to flats that may sit empty for weeks carries more risk, and needs a named responsible person, a written control scheme and routine checks that are recorded.
Why legionella matters
Legionnaires' disease is a potentially fatal form of pneumonia, and HSE notes that everyone is susceptible. People catch it by breathing in small droplets of water carrying the bacteria, for example from a shower. It is not known to spread from person to person. The bacteria multiply in water between 20°C and 45°C, especially where water is stored or recirculated, where it stagnates, and where scale, sludge or other deposits give them something to feed on.
What the law requires
The duty comes from the Health and Safety at Work etc. Act 1974 and the Control of Substances Hazardous to Health Regulations 2002 (COSHH), with practical guidance in HSE's Approved Code of Practice L8 and technical guidance HSG274. HSE guidance confirms the duties apply to residential lettings under a lease or licence of less than seven years, covering private rentals, social housing and hostels.
In practice, the person in control of the premises must identify and assess sources of risk, manage and control those risks, keep appropriate records and review the arrangements regularly, particularly when there is reason to think the assessment is no longer valid, such as after alterations to the system or a change in how the building is used.
Common misunderstandings
- There is no legal requirement for a "legionella test certificate". HSE states this directly, and water sampling is only needed in specific circumstances.
- The law does not set a fixed annual or two-yearly review date for the risk assessment. It should be reviewed regularly and whenever something changes.
- Most landlords of individual homes do not need professional training or accreditation to assess the risk themselves.
- Using a contractor does not transfer responsibility. HSE says you should be satisfied the contractor can do the work to the standard you require.
The controls that do most of the work
HSE sums up the principle as keeping hot water hot, cold water cold and keeping it moving. For a building with stored hot and cold water, HSG274 sets out routine checks that typically include:
- Hot water stored at 60°C or above, and reaching at least 50°C at outlets within one minute.
- Cold water below 20°C within two minutes of running the tap.
- Monthly temperature checks at sentinel outlets, the nearest and furthest outlets from each tank or cylinder.
- Flushing outlets that are used infrequently, weekly or as the risk assessment directs.
- Cleaning and descaling showerheads and hoses quarterly, or as fouling dictates.
- Inspecting cold water storage tanks annually, with tight-fitting lids to keep debris out.
- Removing redundant pipework and dead legs where water can stagnate.
Where outlets deliver water above 44°C there is a scalding risk, so thermostatic mixing valves are often fitted, and these need their own maintenance. Getting the balance between scalding and bacterial growth right is a design and maintenance question, not a one-off setting.
Where residential buildings go wrong
In city centre apartment blocks and build to rent schemes across Liverpool, Manchester and Greater Manchester, the higher-risk situations tend to be predictable: flats left empty between tenancies, guest suites and plant rooms that see little use, communal showers in gyms and changing areas, tanks that have not been opened in years, and alterations made during fit-out that leave capped-off pipes behind. HSE advises that vacant properties should have outlets run at least weekly, with a flushing regime or draining for longer vacancies.
Tenants also have a part to play. HSE suggests telling them not to change the hot water cylinder temperature setting, to clean and disinfect showerheads regularly and to report problems with hot water promptly.
Records worth keeping
Employers with five or more employees must record the significant findings of the assessment. HSE recommends that records cover who is responsible, the assessment findings, the written scheme, whether the system is in use, and the results and dates of monitoring and checks. Monitoring records should be kept for at least five years. Even where writing things down is not strictly required, a clear log is the best evidence that the duty has been met.
How Apex helps
We build water hygiene tasks such as temperature monitoring, flushing of little-used outlets, tank inspections and showerhead descaling into a planned preventative maintenance schedule, and keep the logs alongside your other statutory records under fire safety and compliance. Where a building needs a formal risk assessment or water treatment, we arrange it through suitably competent specialists and track the actions to completion. This guide is general information, not legal advice. Check the current HSE guidance for your own buildings.
Sources
- HSE, Legionella and landlords' responsibilities
- HSE, What is Legionnaires' disease
- HSE, Legionnaires' disease: what you must do
- HSE, Monitoring and keeping records
- HSE, Hot and cold water systems
- HSE, HSG274 Part 2: the control of legionella bacteria in hot and cold water systems
- HSE, Approved Code of Practice L8