Legionella Risk Assessment for Blocks of Flats: Compliance Guide
A comprehensive guide to Legionella risk assessment in blocks of flats, covering HSE Legionella guidance, legal requirements under L8 and HSG274, Legionella testing frequency, managing agent responsibilities, and leaseholder rights regarding water safety in residential buildings. Understand Legionella risk assessment costs, remedial actions, and how to ensure Legionella compliance in your block.
Introduction to Legionella Risk in Blocks of Flats
Legionella is a type of bacteria found naturally in water sources that can cause Legionnaires' disease, a severe and potentially fatal form of pneumonia. In blocks of flats, the communal water systems that serve multiple dwellings can create conditions where Legionella bacteria thrive if not properly managed. Cold water storage tanks in loft spaces, communal hot water plant, lengthy pipe runs, and infrequently used outlets all present potential risks that must be assessed and controlled through a structured Legionella risk assessment.
The responsibility for managing Legionella risk in residential blocks falls on the duty holder, which is typically the freeholder or the managing agent appointed to manage the building on their behalf. This guide explains what a Legionella risk assessment involves, who is responsible, how often assessments are needed, what they cost, and how the results feed into the ongoing water safety management of the block.
Whether you are a freeholder, a director of a residents' management company, or a leaseholder wanting to understand what your service charge contributions are funding, this guide provides a thorough overview of Legionella compliance for residential blocks. For a broader view of health and safety obligations in block management, see our health and safety guide.
Legal Requirements and HSE Guidance
The legal framework for Legionella risk assessment in residential buildings is rooted in general health and safety legislation and supplemented by specific HSE Legionella guidance. Understanding these requirements is essential for any duty holder responsible for a block of flats.
Health and Safety at Work Act 1974
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 persons are not exposed to risks to their health and safety. For residential blocks, this duty extends to the management of communal water systems where there is a foreseeable risk of Legionella exposure. The freeholder or managing agent acting as the duty holder must take appropriate steps to assess and control the risk.
HSE Approved Code of Practice L8
The HSE Approved Code of Practice L8, titled "Legionnaires' disease: The control of Legionella bacteria in water systems," is the primary regulatory guidance for Legionella compliance. It sets out the duties of those responsible for the control of Legionella bacteria in water systems and establishes a framework for identifying and assessing risk, preparing a written scheme for preventing or controlling the risk, implementing and managing the scheme, and keeping records. While L8 has special legal status as an Approved Code of Practice, failure to follow its recommendations can be used as evidence of non-compliance in enforcement proceedings.
HSG274 Part 2: Hot and Cold Water Systems
HSG274 Part 2 provides detailed technical guidance on the control of Legionella in hot and cold water systems, which is the most relevant guidance document for blocks of flats. It covers water system design, temperature control, monitoring regimes, cleaning and disinfection procedures, and the management of infrequently used outlets. Managing agents and water hygiene consultants use HSG274 Part 2 as the benchmark for assessing whether a building's water systems are being managed in accordance with best practice. The guidance is freely available from the HSE website and should be familiar to anyone responsible for water safety in a residential block.
What a Legionella Risk Assessment Covers
A Legionella risk assessment for a block of flats is a systematic evaluation of the building's water systems to identify where conditions may allow Legionella bacteria to proliferate and how occupants could be exposed. The assessment should be carried out by a competent person with the knowledge and experience to evaluate the specific risks associated with the building's water infrastructure.
- Inspection of cold water storage tanks including condition, covers, insulation, and location
- Assessment of hot water generation plant such as calorifiers, cylinders, and boilers
- Survey of pipework distribution systems including identification of dead legs and redundant pipework
- Temperature profiling at sentinel and representative outlets throughout the building
- Identification of infrequently used outlets in communal areas, void flats, and plant rooms
- Evaluation of water treatment measures including any dosing systems or point-of-use filters
- Review of existing maintenance records, temperature logs, and previous assessment reports
- Assessment of the potential for aerosol generation from showers, taps, and other outlets
The assessment will produce a written report with a risk rating for each element of the water system, a prioritised action plan for any remedial works required, and a recommended ongoing monitoring schedule. This report forms the basis of the building's water safety management plan and should be kept on file as evidence of compliance. Managing agents should share relevant findings with directors and, where appropriate, with leaseholders through the block management reporting process.
Testing and Monitoring Requirements
A Legionella risk assessment is not a one-off exercise. The ongoing monitoring and Legionella testing regime is equally important to ensure that the control measures identified in the assessment are being maintained and that the risk remains at an acceptable level.
Temperature Monitoring
Temperature monitoring is the cornerstone of Legionella control in hot and cold water systems. HSG274 Part 2 recommends that hot water should be stored at sixty degrees Celsius and distributed at fifty degrees Celsius or above, while cold water should be maintained below twenty degrees Celsius. Monthly temperature checks at sentinel outlets, which are the nearest and furthest points from the water storage or generation source, are standard practice. Any readings outside of the safe range should be investigated and corrective action taken promptly.
Water Sampling and Microbiological Testing
Where the risk assessment identifies elevated risk, microbiological water sampling may be recommended. This involves collecting water samples from strategic points in the system and sending them to an accredited laboratory for analysis. Samples are typically tested for Legionella pneumophila and the total Legionella species count. The results are reported as colony forming units per litre, and action levels are defined in HSG274 Part 2. If Legionella is detected above the action level, the managing agent must implement immediate corrective measures, which may include thermal disinfection, chemical treatment, or system modifications.
Quarterly and Annual Inspections
In addition to monthly temperature checks, quarterly inspections of cold water storage tanks, showerheads, and other system components are recommended. Annual reviews should include a comprehensive check of all control measures, a review of monitoring records, and a consideration of whether the risk assessment itself needs to be updated. These inspections should be carried out by a competent person and documented as part of the building's health and safety records. A well-maintained monitoring programme demonstrates due diligence and protects the duty holder in the event of an incident.
Responsibilities: Freeholder, Managing Agent, and Leaseholder
Understanding who is responsible for Legionella compliance in a block of flats is critical. The duty holder responsibility under L8 typically falls on the person or organisation that has control of the premises and the water systems within them.
Freeholder Responsibilities
The freeholder, as the owner of the building, is ultimately responsible for ensuring that Legionella risks are assessed and controlled. Where the freeholder retains management of the building, they are the duty holder and must ensure that a Legionella risk assessment is carried out, that the recommendations are implemented, and that an ongoing monitoring programme is in place. Even where management is delegated to a managing agent, the freeholder retains overall responsibility and should satisfy themselves that the agent is fulfilling this obligation on their behalf.
Managing Agent Responsibilities
The managing agent appointed to manage a block of flats will typically assume day-to-day responsibility for Legionella compliance as part of their management duties. This includes commissioning the Legionella risk assessment, instructing remedial works, arranging ongoing monitoring visits, maintaining records, and reporting to directors or the freeholder on compliance status. The managing agent should also ensure that Legionella risk assessment costs and ongoing monitoring expenses are properly budgeted within the service charge.
Leaseholder Responsibilities
Leaseholders are generally not responsible for the communal water systems in a block of flats, but they do have responsibilities within their own demised premises. This includes ensuring that water systems within their flat are properly maintained, that showerheads are cleaned regularly, and that outlets are used frequently enough to prevent stagnation. Leaseholders who are absent for extended periods should arrange for their water systems to be flushed regularly. Leaseholders also have the right to request information about the building's Legionella compliance status and to review the risk assessment report through the managing agent.
Costs, Service Charges, and Budgeting
The costs associated with Legionella risk assessment and ongoing water hygiene management are legitimate building expenses that are typically recoverable through the service charge. Managing agents should ensure that these costs are transparently budgeted and clearly communicated to leaseholders.
Assessment and Monitoring Costs
The Legionella risk assessment cost for a block of flats depends on the size and complexity of the water systems. A basic assessment for a small block may cost a few hundred pounds, while larger buildings with complex communal systems may require assessments costing over a thousand pounds. Ongoing monitoring visits, including monthly temperature checks and quarterly inspections, typically cost between one hundred and three hundred pounds per visit. These are recurring costs that must be factored into the annual service charge budget.
Remedial Works Costs
If the risk assessment identifies issues that need to be addressed, such as replacing a deteriorated cold water storage tank, removing dead legs, installing thermostatic mixing valves, or upgrading insulation, the costs of these communal repairs can be significant. Managing agents should obtain competitive quotations and, where the works exceed the consultation threshold under Section 20 of the Landlord and Tenant Act 1985, carry out the required leaseholder consultation process before proceeding. Remedial works should be prioritised based on the risk ratings in the assessment report.
Budgeting for Legionella Compliance
Effective block management requires that Legionella compliance costs are anticipated and budgeted for, rather than arising as unexpected expenses. The annual service charge budget should include provision for the regular risk assessment cycle, routine monitoring visits, water sampling where recommended, and a contingency for remedial works. Building up a reserve fund contribution for water system improvements helps to spread the cost over time and avoids large one-off demands on leaseholders. Transparent budgeting and clear communication of these costs builds confidence among leaseholders that their building is being responsibly managed.
Remedial Actions and Ongoing Water Management
Completing a Legionella risk assessment is only the first step. The ongoing management of water safety in a block of flats requires a systematic approach to implementing the assessment's recommendations, maintaining control measures, and keeping comprehensive records.
Implementing Remedial Actions
The risk assessment report will typically include a prioritised action plan with recommendations categorised by urgency. High-priority actions, such as addressing water temperatures in the danger zone or repairing damaged cold water tank covers, should be dealt with immediately. Medium-priority actions, such as removing identified dead legs or improving insulation, should be scheduled within a defined timeframe. The managing agent should track the completion of each action item and maintain a record of the works carried out, including dates, contractors used, and costs incurred. This record forms part of the building's compliance evidence.
Written Scheme of Control
L8 requires that a written scheme for controlling the risk of Legionella be prepared and implemented. This scheme should document the control measures in place, the monitoring regime, the responsibilities of those involved in managing the water system, and the procedures for dealing with incidents or adverse test results. The written scheme should be reviewed whenever the risk assessment is updated and should be readily accessible to the block management team, site staff, and any water hygiene contractors working on the building.
Record Keeping and Compliance Evidence
Maintaining thorough records is a fundamental part of Legionella compliance. Records should include the current risk assessment report, the written scheme of control, temperature monitoring logs, water sampling results, details of remedial works completed, maintenance records for water system components, and training records for any personnel involved in water management. These records should be retained for at least five years and must be available for inspection by the HSE or local authority environmental health officers. A well-organised compliance file demonstrates that the duty holder is taking their responsibilities seriously and provides protection in the event of an incident or enforcement action.
Frequently Asked Questions About Legionella Risk Assessment
Do landlords have to do a Legionella risk assessment?
Yes, landlords and those responsible for water systems in residential buildings have a legal duty to carry out a Legionella risk assessment. Under the Health and Safety at Work Act 1974 and the Control of Substances Hazardous to Health Regulations 2002 (COSHH), duty holders must assess and control the risk of exposure to Legionella bacteria in water systems. The HSE Approved Code of Practice L8 provides specific guidance on how to manage these risks. For blocks of flats, the freeholder or managing agent is typically the duty holder responsible for communal water systems such as cold water storage tanks, calorifiers, and any shared hot water plant. Failure to carry out a risk assessment can result in enforcement action by the HSE, including improvement notices and, in serious cases, prosecution. Even where the risk is deemed low, the assessment itself must still be completed and documented to demonstrate compliance with the law.
What should be included in a Legionella risk assessment?
A Legionella risk assessment should include a thorough examination of all water systems within the building, identifying where conditions may allow Legionella bacteria to grow and spread. The assessment must cover the cold water storage tanks, hot water cylinders or calorifiers, pipework distribution systems, any dead legs or infrequently used outlets, water temperature profiles, and the condition of system components. It should also identify who may be at risk of exposure, particularly vulnerable residents such as elderly occupants or those with compromised immune systems. The assessor must evaluate the current control measures in place and recommend any corrective actions needed to reduce the risk. A written report should be produced detailing the findings, risk ratings for each element of the system, and a prioritised action plan with timescales. The assessment should also include a schematic drawing of the water system and a recommended monitoring schedule going forward.
How often do blocks of flats need a Legionella risk assessment?
The HSE does not prescribe a fixed frequency for Legionella risk assessments, but the Approved Code of Practice L8 states that assessments must be reviewed regularly and whenever there is reason to suspect the assessment is no longer valid. In practice, most competent water hygiene consultants recommend that a full Legionella risk assessment for a block of flats is carried out at least every two years. However, the assessment should be reviewed sooner if there are changes to the water system, such as modifications to pipework, replacement of storage tanks or calorifiers, changes in occupancy patterns, or if monitoring results indicate a problem. Ongoing monitoring, including monthly temperature checks and quarterly inspections of water storage tanks, should continue between assessments. Managing agents should ensure that the review schedule is documented and that responsibility for commissioning the next assessment is clearly assigned.
Can you do a Legionella risk assessment yourself?
Technically, there is no legal requirement for a Legionella risk assessment to be carried out by an external specialist, and the HSE guidance states that the duty holder may carry out the assessment themselves provided they are competent to do so. However, competence in this context means having sufficient training, knowledge, and experience to identify Legionella risks within water systems and to recommend appropriate control measures. For blocks of flats with communal water systems, the complexity of the assessment typically requires professional expertise. A competent assessor will understand the microbiology of Legionella, the engineering of water systems, and the regulatory framework including L8 and HSG274 Part 2. In practice, managing agents and freeholders almost always instruct a specialist water hygiene company to carry out the assessment, both to ensure thoroughness and to provide a defensible record of compliance. Attempting a self-assessment without adequate competence could leave the duty holder exposed to liability.
How much does a Legionella risk assessment cost?
The cost of a Legionella risk assessment for a block of flats varies depending on the size and complexity of the water systems in the building. For a small block with a simple cold water storage tank and no communal hot water system, a basic assessment may cost between two hundred and four hundred pounds. Larger blocks with multiple risers, communal hot water plant, calorifiers, and more complex distribution systems will typically cost between five hundred and fifteen hundred pounds. These costs are usually recoverable through the service charge as a legitimate health and safety expense under the terms of the lease. Additional costs may be incurred for remedial works identified by the assessment, ongoing monitoring visits, and water sampling or testing. Managing agents should obtain competitive quotations from accredited water hygiene companies and ensure the scope of work is clearly defined before instructing the assessment. Budget provision for Legionella compliance should be included in the annual service charge budget.
Is Legionella testing mandatory for residential blocks?
While there is no specific standalone regulation that mandates routine Legionella water testing for all residential blocks, the legal duty to assess and control Legionella risk means that testing may be required as part of the overall risk management programme. The HSE Approved Code of Practice L8 and guidance document HSG274 Part 2 set out the expectation that duty holders will implement a monitoring regime proportionate to the level of risk identified in the assessment. Where the risk assessment identifies conditions that could support Legionella growth, such as water temperatures within the danger zone of twenty to forty-five degrees Celsius, stagnation, or the presence of biofilm, the assessor may recommend microbiological sampling and testing as part of the control measures. In blocks with communal hot water systems, regular temperature monitoring is considered essential and quarterly or annual Legionella sampling may be recommended. Managing agents must follow the recommendations of the risk assessment and can be held liable if they fail to implement the prescribed testing regime and a case of Legionnaires disease occurs.
Need Help With Legionella Compliance?
Whether you need a Legionella risk assessment for your block of flats, guidance on meeting HSE Legionella requirements, or a managing agent who takes water safety seriously, Block is here to help. Our experienced team manages Legionella compliance, ongoing monitoring, and remedial works across residential blocks nationwide. See our health and safety guide for further information on our approach.