Landlords are responsible for managing health and safety risks connected with the water systems in properties they control. That includes the risk of exposure to Legionella bacteria. For a typical rented home, however, the legal position is often misunderstood: the duty is to assess and control the risk, not automatically to buy an annual “Legionella certificate” or arrange routine laboratory testing.
This guide explains what London landlords and property managers should consider, when a simple assessment may be sufficient, and when specialist advice may be appropriate.
What does the law require from landlords?
Health and Safety Executive (HSE) guidance states that landlords who provide residential accommodation have a legal duty to ensure that the risk of exposure to Legionella is properly assessed and controlled. The duty can also apply where a letting or managing agent has responsibility for the water system under the management agreement.
The assessment should be proportionate to the property and its water system. HSE guidance recognises that many small domestic-type systems may be low risk, particularly where water turnover is high and the system is straightforward.
A landlord may carry out the assessment personally if they are competent to do so. If they do not have sufficient knowledge of the water system or the relevant risks, they should use a competent person.
Is a Legionella certificate legally required every year?
No general rule requires every residential landlord to obtain an annual Legionella certificate. The important requirement is that the risk is assessed, appropriate controls are put in place where necessary, and the assessment is reviewed when circumstances change or when there is reason to believe it may no longer be valid.
This is different from some other property-safety regimes that have fixed inspection intervals. The appropriate review frequency for Legionella depends on the system and the risks identified.
Does every rented property need Legionella water testing?
No. HSE guidance says microbiological monitoring is not usually required for ordinary hot and cold water systems. Testing may become appropriate where there is doubt about the effectiveness of the control regime, where recommended control parameters are not being consistently achieved, or where the risk assessment identifies a specific reason for sampling.
Where sampling is required, it should be carried out and interpreted by suitably competent providers using appropriate laboratory methods.
What should a landlord’s Legionella risk assessment consider?
The assessment should reflect the actual property rather than rely on a generic checklist alone. Depending on the building, relevant points may include:
- the layout and condition of the hot and cold water system;
- whether water is stored in tanks or cylinders;
- outlets that are rarely used and may allow water to stagnate;
- dead legs, redundant pipework or unusually long pipe runs;
- showers and other outlets capable of producing fine water droplets;
- whether hot and cold water temperatures are being adequately controlled;
- periods when the property is empty or only partly occupied;
- any occupants who may be particularly susceptible to infection; and
- changes to the plumbing system, occupancy or use of the property.
Why London properties can require a property-specific approach
Legionella risk is determined by the water system and how it is used, not by the London postcode. But some property characteristics can make a more careful assessment sensible—for example, converted buildings, HMOs, larger residential blocks, properties with stored water, mixed-use premises, or buildings containing infrequently used outlets.
A modern flat with a simple mains-fed system may present a very different risk profile from a large converted property with multiple bathrooms, stored hot water and sections of pipework that are rarely used.
Practical control measures for low-risk residential systems
Where the assessment identifies a low-risk domestic system, controls are often straightforward. HSE guidance gives examples such as flushing the system before letting a property, preventing debris from entering stored cold water, maintaining appropriate hot-water control parameters, removing redundant pipework where identified, and advising tenants to keep showerheads clean.
Water should not be allowed to stagnate unnecessarily. Properties that have been empty for a period may require flushing before normal occupation resumes. Any temperature-control measures must also take account of scalding risk and the design of the system.
When should the assessment be reviewed?
A Legionella risk assessment should not simply be filed away indefinitely. It should be reviewed when there is a significant change or when there is reason to suspect that the existing assessment is no longer valid. Examples can include alterations to the water system, a change in building use, prolonged vacancy, new information about the system, or evidence that existing controls are not working as intended.
Landlord, agent or managing company: who is responsible?
Responsibility should be clearly defined in the management agreement. HSE guidance states that where a managing or letting agent is used, the contract should specify who is responsible for maintenance and safety checks, including Legionella risk management. If the agreement is unclear, responsibility may remain with the person who controls the premises and water system.
When is a professional Legionella risk assessment useful?
Professional assessment can be appropriate where the landlord or manager is not competent to assess the system, where the water system is more complex, where there are vulnerable occupants, or where previous concerns indicate that a closer review is required.
A competent assessor should look at the actual water system, identify credible sources of risk and recommend controls that are proportionate to the property. A useful assessment should help the dutyholder understand what needs to be done rather than simply provide a generic certificate.
Key point for London landlords
The core obligation is straightforward: understand the water system, assess the risk of exposure to Legionella, control any identified risks and review the assessment when necessary. Do not assume that every property needs annual laboratory testing or a fixed-date certificate; the correct approach depends on the property and its risk profile.
If you need a property-specific assessment in London, see our Legionella Risk Assessment Services or request a quote.
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