Legionella Risk Assessments: Your Legal Obligations as a Landlord

What Is Legionella and Why Should Landlords Care?

Legionella is a genus of bacteria found naturally in freshwater environments such as rivers and lakes. While it poses little threat in these settings, it becomes a serious health hazard when it colonises man-made water systems. When legionella bacteria multiply in warm, stagnant water and are inhaled as fine droplets (aerosols), they can cause Legionnaires' disease, a severe and potentially fatal form of pneumonia.

For landlords and property managers, this is not an abstract concern. Every rental property with a water system, which is to say every rental property, carries some level of legionella risk. Hot and cold water systems, showers, storage tanks, and even rarely used taps can all become breeding grounds for the bacteria if they are not properly maintained.

Certain tenants are particularly vulnerable. Those over 45, smokers, people with chronic respiratory conditions, and individuals with weakened immune systems face a significantly higher risk of developing Legionnaires' disease if exposed. In shared housing, student accommodation, and sheltered housing for older adults, the duty of care is especially acute.

The consequences of neglecting legionella control are severe. Beyond the obvious moral imperative to protect your tenants' health, landlords who fail to manage legionella risk face criminal prosecution, substantial fines, and civil liability claims. In the worst cases, deaths have resulted from poorly maintained water systems in rented properties.

Your Legal Obligations

Landlords in England and Wales have clear legal duties when it comes to legionella control. Several overlapping pieces of legislation and guidance establish these obligations.

The Health and Safety at Work Act 1974 places a general duty on employers and those in control of premises to ensure, so far as is reasonably practicable, that people are not exposed to risks to their health and safety. For landlords, this extends to tenants and visitors in their properties.

The Control of Substances Hazardous to Health Regulations 2002 (COSHH) require duty holders to assess and prevent or control the risk from exposure to hazardous substances, including biological agents like legionella bacteria.

The most specific guidance comes from the HSE Approved Code of Practice L8 (Legionnaires' disease: The control of legionella bacteria in water systems) and its accompanying technical guidance documents HSG274 Parts 1, 2, and 3. While L8 and HSG274 are not themselves law, they carry significant legal weight. Courts treat compliance with an Approved Code of Practice as strong evidence that you have met your legal duties; conversely, failure to follow the guidance places the burden on you to demonstrate that you controlled the risk by other equally effective means.

Under L8, as a landlord you must:

- Identify and assess sources of legionella risk in your properties
- Prepare a written scheme for preventing or controlling the risk
- Implement, manage, and monitor precautions
- Keep records of your precautions
- Appoint a competent person to help you comply with your duties

It is worth noting that you cannot contract out of these responsibilities. Even if you use a letting agent or property manager, the legal duty remains with the person in control of the premises. You can delegate tasks, but you must ensure they are carried out competently.

What Does a Legionella Risk Assessment Involve?

A legionella risk assessment is a systematic review of your property's water systems to identify conditions that could allow legionella bacteria to grow and spread. It must be carried out by a competent person, either someone with appropriate training and experience within your organisation or, more commonly for landlords, an external specialist.

The assessment typically covers several key areas.

Water system survey. The assessor will map out the entire water system in the property, including the cold water supply, hot water system, storage tanks, cylinders, pipes, outlets, showers, and any other water-using equipment. They will identify the type and age of components, materials used, and the overall system configuration.

Temperature checks. Legionella bacteria thrive between 20°C and 45°C, with optimal growth occurring between 25°C and 42°C. The assessor will measure water temperatures at various points throughout the system. Hot water should be stored at 60°C or above and delivered at taps at 50°C or above within one minute. Cold water should be below 20°C.

Identification of risk factors. The assessor will look for specific conditions that promote bacterial growth. These include:

- Dead legs (sections of pipework that are capped off or rarely used, where water can stagnate)
- Infrequently used outlets such as guest bathrooms or utility room taps
- Cold water storage tanks that are uncovered, poorly insulated, or oversized for the property's needs
- Shower heads and hoses that may harbour biofilm
- Flexible hoses and other fittings where water can pool
- Limescale and corrosion that provide nutrients for bacterial growth

Tenant vulnerability. The assessment should consider the occupants of the property. A house in multiple occupation (HMO) with shared facilities, or a property let to older or immunocompromised tenants, may require more stringent control measures.

Written report. Following the survey, you will receive a detailed report identifying the risks found and recommending specific actions to control them. This report forms the basis of your ongoing legionella management scheme.

For most straightforward domestic rental properties, a legionella risk assessment can be completed in one to two hours. More complex properties, such as large HMOs or buildings with older or more extensive water systems, will take longer.

How Often Should Assessments Be Carried Out?

HSE guidance does not prescribe a fixed interval for legionella risk assessments, but the widely accepted industry standard is to carry out a full assessment at least every two years. Many water hygiene professionals and insurers recommend annual assessments for higher-risk properties such as HMOs, sheltered housing, and buildings with complex water systems.

Beyond the periodic full assessment, you should review your risk assessment whenever there is a significant change that could affect legionella risk. This includes:

- Changes to the water system, such as installing new pipework, replacing a boiler, or adding a shower
- A change of use for the property or a change in tenant profile
- Any indication that the existing control measures are no longer effective
- Following a case or suspected case of Legionnaires' disease linked to the property

In addition to the risk assessment itself, ongoing monitoring is essential. This means carrying out regular temperature checks (monthly is considered good practice), inspecting water storage tanks annually, and ensuring that all control measures identified in your risk assessment are being maintained consistently.

For properties that sit vacant between tenancies, legionella risk increases significantly because stagnant water is one of the primary conditions for bacterial growth. You should ensure that water systems in void properties are either flushed regularly (at least weekly) or properly drained down and isolated.

Practical Steps to Reduce Legionella Risk

While a professional risk assessment will provide recommendations tailored to your specific property, there are several practical measures that apply to virtually all rental properties.

Maintain correct water temperatures. This is the single most effective control measure. Ensure your hot water cylinder thermostat is set to 60°C or above. Hot water should reach outlets at 50°C or above within one minute of running the tap. Cold water should remain below 20°C; if cold pipes run through warm areas such as airing cupboards, they may need insulating.

Flush infrequently used outlets. Any tap, shower, or other water outlet that is not used for a week or more should be flushed by running both hot and cold water for at least two minutes. If you manage the property, include this in your void property procedures. If tenants are responsible, provide clear written guidance on the importance of running all taps regularly.

Remove or manage dead legs. Where sections of redundant pipework exist, have them physically removed rather than simply capped off. If removal is not practicable, ensure they are as short as possible and that water in them is regularly displaced.

Maintain and clean water storage tanks. Cold water storage tanks should be properly covered, insulated against heat gain, and sized appropriately for the property's demand. Oversized tanks allow water to sit for longer, increasing stagnation risk. Tanks should be inspected annually and cleaned or disinfected if any contamination is found.

Descale and disinfect showers and taps. Shower heads, hoses, and tap aerators should be cleaned and descaled quarterly. Limescale deposits provide both a physical surface and nutrients for biofilm, the slimy layer in which legionella bacteria thrive.

Ensure adequate water turnover. Properties with very low water usage may need additional measures to ensure that water does not sit in the system for extended periods. Consider whether the system design is proportionate to actual usage patterns.

Address system defects promptly. If your risk assessment identifies issues such as damaged tank lids, failed temperature controls, or corroded pipework, address them without delay. Prioritise repairs based on the level of risk they present.

Record Keeping and Documentation

Good record keeping is not merely administrative; it is a legal requirement and your primary evidence of compliance if you are ever investigated or prosecuted.

You should maintain the following records for each property:

- The current legionella risk assessment report, including the date of assessment, the name and qualifications of the assessor, findings, and recommended actions
- A written control scheme describing the measures in place to manage legionella risk, who is responsible for each task, and the frequency of each action
- Temperature monitoring records, including dates, locations, and readings for both hot and cold water
- Maintenance and inspection records for water storage tanks, shower heads, TMVs (thermostatic mixing valves), and other relevant equipment
- Records of remedial actions taken, with dates and details of any defects found and how they were resolved
- Tenant communication records, including any written guidance provided to tenants about flushing taps or reporting issues

These records should be kept for the duration of their relevance and for at least five years afterwards. In practice, many landlords find it easiest to maintain a rolling file for each property that includes the current risk assessment and all monitoring records since the last assessment.

Digital record keeping is perfectly acceptable and, for portfolio landlords, far more practical than paper files. Property management software that allows you to log tasks, store documents, and set reminders for periodic checks can significantly reduce the administrative burden while improving compliance.

If you are a landlord or property manager responsible for multiple properties, establishing a standardised legionella management procedure across your portfolio will help ensure consistency and make it easier to demonstrate compliance during any audit or inspection.

Taking Legionella Compliance Seriously

Legionella risk management is not optional, and it is not something that can be addressed with a one-off assessment and then forgotten. It requires an ongoing commitment to monitoring, maintenance, and record keeping. The good news is that for most domestic rental properties, the risk is relatively low and the control measures are straightforward and inexpensive.

By commissioning regular risk assessments, maintaining proper water temperatures, ensuring good water turnover, and keeping thorough records, you protect your tenants' health, meet your legal obligations, and safeguard yourself against prosecution and liability claims. It is one of those areas of property compliance where a modest, consistent investment of time and money delivers significant peace of mind.