ACOP L8 is the HSE's Approved Code of Practice for legionella control. It has special legal status — if you're prosecuted and haven't followed L8, you must prove you achieved compliance another way, or a court will find you at fault. Understanding what L8 requires is essential for anyone responsible for water systems.
How confident are you in your L8 compliance?
Be honest — this helps you focus on the right areas.
What is ACOP L8?
ACOP L8 — officially titled "Legionnaires' disease: The control of legionella bacteria in water systems" — is the Health and Safety Executive's Approved Code of Practice. Now in its fourth edition (2013), it sets out what duty holders must do to identify and control legionella risks.
ACOP L8 has special legal status. While not law itself, courts treat it as the benchmark for compliance. If you follow L8, you have a strong defence. If you don't, you must prove you achieved equivalent protection another way.
Who must comply with L8?
Anyone who is a "duty holder" under health and safety law:
- Employers with premises containing water systems
- Landlords (including residential landlords)
- Those in control of premises — building owners, facility managers, managing agents
- Care providers — care homes, hospitals, healthcare settings
- Anyone responsible for water systems in commercial, public, or rented buildings
If you have any control over water systems where people could be exposed to legionella, L8 applies to you.
The six core requirements of ACOP L8
L8 establishes six fundamental duties for all duty holders. Our downloadable checklist covers each of these in detail.
1. Identify and assess sources of risk
You must conduct a suitable and sufficient legionella risk assessment that:
- Identifies all water systems and potential legionella sources
- Evaluates the likelihood of bacterial growth and human exposure
- Assesses who might be at risk (including vulnerable groups)
- Is conducted by a competent person
- Is documented in writing
Checklist items include: Assessment conducted, competent assessor used, all systems identified, schematics documented, review date set.
2. Appoint a responsible person
You must designate someone to take day-to-day responsibility for legionella control. This person must:
- Be competent (through training, qualifications, or experience)
- Have sufficient authority to implement control measures
- Have adequate time and resources for the role
- Have a deputy for periods of absence
Checklist items include: Named person appointed, competence verified, authority granted, deputy identified.
3. Prepare a written scheme of control
Based on your risk assessment, you must create a written scheme that documents:
- What control measures will be implemented
- Who is responsible for each task
- How often each task must be carried out
- What records must be kept
- Emergency and remedial action procedures
Checklist items include: Scheme exists, control measures specified, responsibilities assigned, frequencies documented.
4. Implement the control scheme
Having a scheme is not enough — you must actively implement it:
- Carry out all specified control measures
- Conduct temperature monitoring as scheduled
- Flush infrequently used outlets
- Clean and maintain water systems
- Respond to out-of-range results
Checklist items include: Temperature monitoring conducted, targets met, flushing regime followed, maintenance completed.
5. Keep records
You must maintain comprehensive records of:
- The risk assessment and any reviews
- The written scheme of control
- All monitoring activities (temperatures, inspections)
- Maintenance and cleaning work
- Any remedial actions taken
- Training provided to staff
Records must be kept for at least 5 years.
Checklist items include: Assessment retained, monitoring records kept, maintenance documented, 5-year retention.
6. Review and monitor
Legionella control is not a one-off exercise. You must:
- Review the risk assessment at least every 2 years
- Review immediately if circumstances change (system modifications, building use changes, control failures)
- Monitor that control measures remain effective
- Update the written scheme as needed
Checklist items include: Review schedule in place, last review dated, changes trigger reassessment.
Many organisations conduct a risk assessment but fail to implement ongoing controls or keep adequate records. This is one of the most common compliance failures and a frequent cause of HSE enforcement action.
Critical temperature requirements
Temperature control is your primary defence against legionella growth. L8 and HSG274 specify:
| System | Target Temperature | Why It Matters |
|---|---|---|
| Hot water storage | 60°C or above | Kills legionella bacteria |
| Hot water at outlets | 50°C+ within 1 minute | Prevents growth in distribution |
| Cold water storage | Below 20°C | Too cold for significant growth |
| Cold water at outlets | Below 20°C | Maintains cold chain |
Temperatures between 20-45°C are the danger zone where legionella thrives.
If you can't achieve these temperatures, you need additional controls such as chemical treatment or increased monitoring frequency.
What happens if you're not compliant?
The HSE takes legionella control seriously, particularly after outbreaks.
Potential consequences
- Improvement notices requiring specific actions within a deadline
- Prosecution with unlimited fines
- Imprisonment for up to 2 years in serious cases
- Corporate manslaughter charges if death results from negligence
- Civil claims from those who contract Legionnaires' disease
- Reputational damage — outbreaks attract significant media attention
Company fined after legionella control failures
An HSE inspection found systematic failures in legionella management at commercial premises despite no outbreak occurring.
- ✗Risk assessment was 4 years old and never reviewed
- ✗No named responsible person
- ✗Written scheme existed but wasn't being followed
- ✗Temperature monitoring records had 6-month gaps
- ✗Showerheads hadn't been cleaned for over 2 years
The company was fined £85,000 plus costs. An improvement notice required immediate remediation and appointment of an external water hygiene company.
You don't need an outbreak to be prosecuted. HSE conducts proactive inspections and expects to see evidence of ongoing compliance, not just documentation.
Source: Based on HSE enforcement records
L8 compliance by premises type
Different premises face different levels of scrutiny and risk.
Simple vs Complex Systems
Simple Systems
- •Small office with basic plumbing
- •Single residential rental property
- •Standard domestic-style water systems
- •No cooling towers or spa pools
- •Regular daily use of all outlets
- •DIY assessment may be appropriate
Complex/High-Risk Systems
- •Care homes, hospitals, healthcare
- •Hotels with variable occupancy
- •Cooling towers or evaporative condensers
- •Spa pools or water features
- •Large buildings with long pipe runs
- •Professional assessment essential
Bottom line: Simple systems still require L8 compliance but the assessment and controls can be proportionate. Complex systems need professional expertise and more rigorous monitoring.
Landlords
All landlords have L8 duties, including residential landlords:
- HMOs and blocks of flats — Full assessment and controls for communal systems
- Single-let properties — Basic assessment, tenant information, between-tenancy checks
- Holiday lets — Higher risk due to irregular use, more frequent flushing needed
Care homes and healthcare
Enhanced requirements due to vulnerable occupants:
- Professional assessment essential
- Weekly or more frequent temperature monitoring
- CQC expects robust water safety management
- Staff training on legionella awareness
- Water sampling programme often required
Commercial premises
Standard L8 compliance required:
- Risk assessment by competent person
- Written scheme proportionate to risk
- Monthly temperature monitoring typical
- Records for HSE inspection
Frequently asked questions
ACOP L8 requires review at least every 2 years. However, you must also review immediately if: water systems are modified, building use changes significantly, there's a suspected legionella case, monitoring shows control measures aren't working, or after extended building closure. Care homes and high-risk premises often review annually.
For simple systems (small office, simple rental property with standard plumbing), you may be able to assess yourself if you're competent — meaning you have appropriate training and understand legionella risks. For complex systems, cooling towers, care homes, or healthcare settings, professional assessment is strongly recommended and often essential.
L8 doesn't mandate specific qualifications, but the responsible person must be 'competent.' This typically means completing legionella awareness training (half-day to 2-day courses are available), understanding your specific water systems, and having authority to implement controls. For complex premises, higher-level qualifications like City & Guilds or BOHS certificates may be appropriate.
ACOP L8 recommends keeping records for at least 5 years. However, best practice is to keep them indefinitely or for as long as you control the premises. Care homes and healthcare settings often keep records for 10+ years. In the event of a legionella case, historical records become crucial evidence.
Not always. L8 emphasises that temperature control and preventing stagnation are the primary controls. Routine water sampling is not required for most systems if controls are effective. However, sampling may be needed for: cooling towers (quarterly testing required), complex or high-risk systems, verifying remedial actions, or where your risk assessment identifies it as necessary.
ACOP L8 sets out the legal duties and has special legal status. HSG274 (Parts 1, 2, and 3) provides detailed technical guidance on how to control legionella in specific systems: Part 1 covers cooling towers, Part 2 covers hot and cold water systems, Part 3 covers other systems like spa pools. You need both — L8 for the 'what' and HSG274 for the 'how.'
Yes. While the HSE has clarified that simple domestic properties may need only basic assessment, landlords still have duties under COSHH to assess and control legionella risks in properties they rent out. HMOs and properties with communal water systems require more comprehensive assessment and controls.
ACOP L8 and HSG274 specify: hot water should be stored at 60°C or above (this kills legionella), and distributed so it reaches outlets at 50°C or above within 1 minute of running. Cold water should be stored and distributed below 20°C. Thermostatic mixing valves (TMVs) can be fitted at outlets to prevent scalding while maintaining safe storage temperatures.
Next steps
Understand what a legionella risk assessment involves:
L8 Risk Assessment: What's Required Under ACOP L8 →
Learn how to create your written scheme of control:
Legionella Written Scheme: What to Include & How to Comply →
Check if you need an assessment:
Do I Need a Legionella Risk Assessment? →
Need help achieving ACOP L8 compliance? A qualified water hygiene specialist can assess your systems, create a compliant written scheme, and support you with ongoing monitoring and record keeping.
Related articles:
- L8 Risk Assessment guide
- Legionella Written Scheme guide
- Landlord legionella responsibilities
- What is legionella?
Useful resources:
- HSE ACOP L8 — Official guidance document
- HSG274 Part 2 — Hot and cold water systems guidance
- Legionella Control Association: legionellacontrol.org.uk
Tools:
Disclaimer: This guidance is based on ACOP L8 and HSE guidance. It does not constitute legal or professional advice. For complex systems or high-risk premises, consult a qualified water hygiene specialist. Requirements may vary based on your specific circumstances. Always refer to the current edition of ACOP L8 and HSG274 for authoritative guidance.