Legionella Written Scheme: What to Include & How to Comply

A written scheme of control is not just paperwork. It's your practical action plan for preventing legionella bacteria from growing in your water systems and making people ill. If you have a legionella risk assessment, you need a written scheme that explains exactly what you're going to do about the risks identified.

What is a written scheme of control?

A written scheme of control is a detailed document that sets out:

• What control measures you will implement to prevent legionella growth
• Who is responsible for each task
• When tasks should be carried out (daily, weekly, monthly, etc.)
• How tasks should be performed
• Where records will be kept

Think of it as the operational manual for keeping your water systems safe. While your risk assessment identifies the hazards, the written scheme is your action plan for managing them.

Why is a written scheme required?

Legal requirement under ACOP L8

The HSE's Approved Code of Practice L8 states:

"Where a legionella risk is identified, a written scheme for controlling the risk should be prepared and implemented."

This isn't optional. If your risk assessment identifies legionella hazards (which most water systems will), you must have a written scheme explaining how you'll control them.

COSHH Regulations 2002

Under COSHH (Control of Substances Hazardous to Health), you must:

1. Prevent exposure to hazardous substances where reasonably practicable, or
2. Control exposure where prevention is not possible
3. Maintain, examine and test control measures
4. Monitor the exposure of employees
5. Keep records

A written scheme demonstrates compliance with these requirements for legionella bacteria, which are classified as biological agents hazardous to health.

Demonstrating due diligence

If someone contracts Legionnaires' disease and your premises is investigated, the HSE will expect to see:

• A suitable and sufficient risk assessment
• A written scheme of control
• Records proving the scheme has been implemented
• Evidence of regular monitoring and review

Without these, you may face prosecution, unlimited fines, or even imprisonment in serious cases.

The link between risk assessment and written scheme

These two documents work together:

The risk assessment answers: What could go wrong?

The written scheme answers: What will we do to stop it?

Key contents of a written scheme

A compliant written scheme of control should include the following elements:

1. Responsible persons

Who is accountable for water safety?

The scheme must clearly identify:

• Duty holder: The person with overall legal responsibility (usually employer, landlord, or building owner)
• Responsible person: The competent person appointed to manage legionella control day-to-day
• Deputies: Who covers when the responsible person is absent
• Additional responsibilities: Who performs specific tasks (temperature checks, flushing, maintenance)

Example:

Duty holder: John Smith, Managing Director
Responsible person: Sarah Jones, Facilities Manager
Deputy: Michael Brown, Deputy Facilities Manager
Temperature monitoring: David Wilson, Maintenance Technician

2. Description of water systems

What systems are you controlling?

Include:

• Schematic drawings of hot and cold water systems
• Location of storage tanks, calorifiers, pumps
• Identification of high-risk areas (showers, cooling towers, spa pools)
• Sentinel taps (representative outlets for monitoring)
• Dead legs or rarely used outlets
• Any recent changes or modifications

This links directly to the system description in your risk assessment.

3. Control measures

What are you doing to prevent legionella growth?

Detail the specific control measures you'll implement. Common controls include:

Temperature control:

• Hot water stored at 60°C or higher
• Hot water delivered at 50°C or higher within one minute
• Cold water stored below 20°C
• How you'll maintain these temperatures

Water turnover:

• Flushing regime for little-used outlets (frequency and duration)
• Which outlets are included in flushing schedules
• Procedure for seasonal closures or vacant periods

System cleanliness:

• Descaling and disinfection of showerheads (frequency)
• Cleaning and disinfection of water tanks (annually or as needed)
• Removal of dead legs or redundant pipework
• Prevention of contamination (tank lids, insulation)

Design and maintenance:

• Planned maintenance schedule
• Inspection regime
• Replacement of failed components
• Procedures for system modifications

4. Monitoring procedures

How will you check controls are working?

Specify:

Temperature monitoring:

• Sentinel outlets to be checked
• Frequency (weekly, monthly)
• Acceptable temperature ranges
• What to do if temperatures are out of range

Visual inspections:

• What to look for (corrosion, scale, biofilm, damaged insulation)
• Frequency (quarterly, annually)
• Who conducts inspections

Water sampling and testing:

• Whether routine testing is required (not always necessary)
• Frequency if required
• Which locations to sample
• Action levels for colony counts

Example monitoring schedule:

• Weekly: Flush little-used outlets for 2 minutes
• Weekly: Check temperature at sentinel hot tap (target: above 50°C)
• Weekly: Check temperature at sentinel cold tap (target: below 20°C)
• Monthly: Visual inspection of calorifier and expansion vessels
• Quarterly: Descale and disinfect all showerheads
• Annually: Clean and disinfect cold water storage tanks

5. Responsibilities and training

Who does what, and are they competent?

• Assign specific tasks to named individuals or roles
• Training requirements for those carrying out control measures
• Competency assessment for the responsible person
• Succession planning for key roles

Ensure anyone carrying out legionella control tasks understands:

• Why legionella control is important
• What could go wrong if tasks aren't completed
• How to perform tasks correctly
• What to do if they identify a problem

6. Emergency procedures

What if something goes wrong?

Include procedures for:

• Out-of-range temperatures: Who to notify, immediate actions
• Suspected legionella case: Reporting, investigation, system shutdown if needed
• System failures: Emergency contacts, isolating affected systems
• Building closures: Shutdown and recommissioning procedures

Example:

If hot water temperature falls below 50°C:
1. Notify Facilities Manager immediately
2. Increase boiler temperature setting
3. Re-check temperature after 2 hours
4. If still below 50°C, call heating engineer (contact: 01234 567890)
5. Record action taken in log book

7. Record keeping

What records must be kept?

Specify:

• Log books for temperature checks, flushing, inspections
• Maintenance records for all work on water systems
• Water sampling results if testing is conducted
• Training records for staff carrying out control tasks
• Incident reports for any problems or failures
• Review dates for risk assessment and scheme updates

Records must be kept for at least 5 years, and longer for care homes and healthcare premises.

8. Review arrangements

How will you keep the scheme current?

Detail:

• Review frequency: At least every 2 years (more often for high-risk premises)
• Triggers for review: System changes, building alterations, legionella case, control failures
• Who conducts reviews: Responsible person, external specialist
• How updates are documented and communicated

Who is responsible for implementing the scheme?

The duty holder

This is the person with overall legal responsibility. Typically:

• Employers for business premises
• Landlords for rental properties
• Registered managers for care homes
• Trustees for charities and community organisations
• Building owners or those in control of premises

The duty holder can delegate tasks but remains ultimately accountable.

The responsible person

The duty holder must appoint a competent person to manage legionella control day-to-day. This person should:

• Have sufficient authority to make decisions and allocate resources
• Understand legionella risks and control measures
• Have adequate training (formal qualifications or demonstrable experience)
• Be given sufficient time and resources to perform the role
• Have clear responsibilities documented in the written scheme

For simple systems, this might be an in-house facilities manager. For complex or high-risk systems, you may need an external water hygiene specialist.

Staff carrying out tasks

Anyone performing monitoring, maintenance, or control tasks must:

• Be competent to carry out their specific duties
• Understand why tasks are important
• Know what to do if they identify problems
• Keep accurate records of work completed

Implementing the scheme

Having a written scheme means nothing if you don't follow it. Implementation requires:

1. Communication

• Ensure all responsible persons have access to the scheme
• Provide copies to anyone carrying out control tasks
• Make sure staff understand their responsibilities
• Display monitoring schedules in relevant locations (plant rooms, maintenance offices)

2. Resource allocation

• Provide adequate time for staff to complete tasks
• Ensure necessary equipment is available (thermometers, flushing taps tools, PPE)
• Budget for maintenance, testing, and professional support
• Cover for staff absence (trained deputies)

3. Supervision and verification

• Check that tasks are being completed as scheduled
• Review log books regularly
• Investigate any gaps in records
• Verify that staff are following procedures correctly

4. Continuous improvement

• Learn from incidents or near-misses
• Update procedures when better methods are identified
• Act on recommendations from audits or inspections
• Keep up to date with HSE guidance and industry best practice

Record keeping requirements

What records must you keep?

The HSE expects comprehensive records of:

Temperature monitoring:

• Date and time of checks
• Location (sentinel taps)
• Temperatures recorded
• Action taken if out of range
• Name of person conducting checks

Flushing regime:

• Date and time of flushing
• Outlets flushed
• Duration (typically 2-5 minutes)
• Any issues identified (low flow, debris, unusual smell)
• Name of person conducting flushing

Maintenance and cleaning:

• Date of work
• What was done (descaling showerheads, cleaning tanks, repairs)
• Findings (scale build-up, corrosion, biofilm)
• Parts replaced
• Contractor details if external work

Water sampling and testing:

• Date of sampling
• Locations sampled
• Laboratory results (colony counts)
• Action taken based on results

Inspections and audits:

• Date of inspection
• What was inspected
• Findings and recommendations
• Action taken

Training:

• Who was trained
• Date and content of training
• Trainer details
• Competency assessment results

Incidents and failures:

• Temperature failures
• System breakdowns
• Suspected or confirmed legionella cases
• Actions taken

How long to keep records?

Minimum 5 years for most premises.

Longer for:

• Care homes and healthcare facilities (often 10 years or permanently)
• Any premises where a legionella case has occurred
• Cooling towers (notification records must be kept for 2 years after tower is decommissioned)

Record formats

Records can be kept:

• Paper log books: Simple and reliable for routine checks
• Electronic systems: Spreadsheets, databases, specialist software
• Mobile apps: Some water hygiene companies provide apps for on-site recording
• Combination: Paper records transferred to electronic storage

Whatever format you use:

• Keep records secure and backed up
• Ensure they're accessible for HSE inspections or investigations
• Maintain clear, legible, accurate records
• Don't falsify records (this can lead to prosecution)

Review and update requirements

When to review your written scheme

Review your written scheme:

At least every 2 years as a matter of routine (more frequently for high-risk premises like care homes - often annually).

Immediately when:

• Water system changes: New equipment, alterations, extensions, removal of systems
• Building use changes: Different occupants, change of business activities, new vulnerable occupants
• Control measures fail: Persistent temperature problems, system breakdowns
• After a legionella case: Any suspected or confirmed case linked to your premises
• Monitoring indicates problems: Positive water samples, recurring issues
• After long closures: Building empty for weeks or months (COVID-19 closures, seasonal closures)
• Regulatory recommendations: Following HSE inspection or professional audit

What to review

Check:

• Are responsible persons still in post? Update names and contact details
• Are control measures still appropriate and effective?
• Have any water systems been added, removed, or modified?
• Are monitoring schedules still being completed?
• Do procedures need updating based on experience?
• Has HSE guidance or industry best practice changed?
• Are there new or emerging risks?

Documenting reviews

Keep records of:

• Date of review
• Who conducted the review
• What was reviewed
• Findings and recommendations
• Changes made to the scheme
• Sign-off by duty holder or responsible person

UK regulatory context

Health and Safety at Work Act 1974

Places a duty on employers and those in control of premises to ensure health and safety, including managing legionella risks through risk assessments and control schemes.

Control of Substances Hazardous to Health Regulations 2002 (COSHH)

Specifically requires:

• Regulation 6: Duty to prevent or adequately control exposure to hazardous substances (including legionella)
• Regulation 7: Maintenance, examination, and testing of control measures
• Regulation 9: Monitoring exposure
• Regulation 10: Health surveillance (for high-risk exposures)
• Regulation 12: Information, instruction, and training

A written scheme demonstrates compliance with these requirements.

ACOP L8: Legionnaires' disease

The HSE's Approved Code of Practice provides detailed guidance. Key requirements:

• Paragraph 36: "The written control scheme should outline methods for controlling risk and the appropriate precautions to be adopted."
• Paragraph 40: "Assign the management responsibilities to a competent person."
• Paragraph 41: "Keep records of the precautionary measures."

While L8 is not law itself, courts treat ACOPs as the standard for what is "reasonably practicable." Failure to follow L8 guidance can be used as evidence of a breach of COSHH or the Health and Safety at Work Act.

HSG274 Parts 1, 2, and 3

These HSE guidance documents provide detailed technical advice on:

• Part 1: Evaporative cooling systems (cooling towers)
• Part 2: Hot and cold water systems
• Part 3: Other risk systems (spa pools, humidifiers, etc.)

Your written scheme should reference appropriate HSG274 guidance for your specific systems.

Enforcement

The Health and Safety Executive (HSE) and local authorities enforce legionella regulations. They can:

• Inspect premises and demand to see your risk assessment and written scheme
• Issue improvement notices requiring specific actions within a timeframe
• Issue prohibition notices stopping use of systems until risks are controlled
• Prosecute for breaches of COSHH or the Health and Safety at Work Act
• Bring charges of manslaughter if legionella deaths result from gross negligence

Penalties include unlimited fines and up to 2 years' imprisonment for individuals.

Common questions

Different schemes for different settings

Small offices and commercial premises

Typical requirements:

• Simple scheme (5-10 pages)
• Basic temperature monitoring (monthly)
• Flushing schedule for holiday closures
• Annual tank inspection and cleaning
• One responsible person (facilities or office manager)

Key focus: Keeping it simple but documented.

Landlords and rental properties

Simple single-let properties:

• Basic control plan (may not need full scheme)
• Document simple checks and tenant responsibilities
• Flushing regime after vacancies
• Basic temperature verification

HMOs and multi-let properties:

• Full written scheme required
• Regular monitoring of common systems
• Flushing schedule for vacant rooms
• Tenant information and responsibilities
• Professional assessment recommended

Key focus: Clarity on landlord vs tenant responsibilities.

Care homes and healthcare facilities

Comprehensive requirements:

• Detailed written scheme (30+ pages common)
• Weekly or daily temperature monitoring
• Frequent flushing of little-used outlets
• Quarterly showerhead cleaning and disinfection
• Monthly calorifier and TMV checks
• Annual tank cleaning and disinfection
• Water sampling programme
• Multiple responsible persons and deputies
• Staff training programme
• Detailed records (keep for 10 years)

Key focus: Protecting vulnerable residents with robust controls.

Hotels, leisure centres, and accommodation

Requirements:

• Comprehensive scheme covering all systems
• Room-by-room flushing regime after vacancy
• Temperature monitoring (weekly)
• Pool and spa water treatment logs
• Housekeeping staff training on flushing
• Emergency procedures for suspected cases
• Seasonal closure and reopening protocols if applicable

Key focus: Managing variable occupancy and multiple high-risk systems.

Industrial sites with cooling towers

Strict requirements:

• Very detailed written scheme (50+ pages typical)
• Daily visual inspections
• Weekly water sampling and testing
• Monthly cleaning and treatment programmes
• Automatic monitoring systems
• Detailed chemical treatment logs
• Notification to local authority
• Specialist contractor involvement
• Emergency shutdown procedures

Key focus: Controlling the highest-risk system with rigorous procedures.

Getting started with your written scheme

If you need to create or update your written scheme:

Step 1: Start with your risk assessment

Your written scheme must address the risks identified in your assessment. If you don't have a current risk assessment, that's your first priority.

Step 2: Identify responsible persons

Decide who will be responsible for:

• Overall accountability (duty holder)
• Day-to-day management (responsible person)
• Carrying out specific tasks (temperature checks, flushing, etc.)

Ensure they're competent or provide training.

Step 3: Document your water systems

Include:

• Schematic diagrams
• Location of tanks, calorifiers, sentinel taps
• High-risk systems requiring specific controls

Step 4: Define control measures

Based on your risk assessment, specify:

• Temperature control procedures
• Flushing regimes
• Cleaning and maintenance schedules
• Monitoring arrangements

Step 5: Create procedures and schedules

Write clear, step-by-step procedures for each control task. Create monitoring schedules showing what needs to be done and when.

Step 6: Set up record keeping

Design log books or electronic records to capture:

• Temperature checks
• Flushing activities
• Maintenance work
• Training records

Step 7: Communicate and implement

• Provide copies to all responsible persons
• Train staff on their duties
• Start following the scheme immediately
• Supervise and verify compliance

Step 8: Review regularly

Schedule reviews (at least every 2 years) and update the scheme when circumstances change.

Related content

• Do I need a legionella risk assessment?
• What is legionella?
• Landlord legionella responsibilities
• Water system safety checker tool