What Is ACOP L8?
ACOP L8 — 'Legionnaires' disease: The control of legionella bacteria in water systems' — is the HSE's Approved Code of Practice. Published alongside the technical guidance documents HSG274 Parts 1–3, it provides the practical framework for managing legionella risks in all types of buildings.
While not legislation itself, ACOP L8 has special legal status. If you're prosecuted for a legionella-related offence, a court will examine whether you followed the ACOP's guidance. If you haven't, you'll need to demonstrate your alternative approach was equally effective — a very difficult argument to sustain.
Who Must Comply
The duties under ACOP L8 apply to a wide range of people and organisations. If you have any control over a building with a water system, you almost certainly have legal obligations.
| Duty Holder | Responsibilities | Common Gaps |
|---|---|---|
| Landlords | Risk assessment, control measures, tenant communication | No assessment, or outdated assessment |
| Facilities managers | Day-to-day management, monitoring, record-keeping | Inconsistent monitoring, poor records |
| Building owners | Appointing competent persons, providing resources | No competent person appointed |
| Employers | Protecting employees from waterborne risks | Water systems overlooked in H&S policy |
| Housing associations | Portfolio-wide compliance programmes | Inconsistent standards across estates |
| NHS / public sector | Enhanced duty of care for vulnerable occupants | Complex estates with legacy issues |
The Five Key Requirements
ACOP L8 can be distilled into five core obligations. Every property manager should be able to confirm they are meeting all five. If any are missing, you have a compliance gap that needs addressing.
- •1. Appoint a competent 'responsible person' — someone with the authority, training, and resources to manage legionella risks
- •2. Carry out a suitable and sufficient risk assessment — by a competent person, documented in writing, and kept up to date
- •3. Implement a written scheme of control measures — specific actions to prevent legionella growth, based on the risk assessment findings
- •4. Maintain records — of all risk assessments, monitoring results, maintenance actions, and control measures
- •5. Review and update regularly — at least every two years, or whenever there are relevant changes to the building or water system
Monitoring Schedule
Consistent monitoring is the backbone of ACOP L8 compliance. The table below shows the minimum recommended monitoring frequencies based on HSG274 guidance. Your specific risk assessment may require more frequent monitoring in higher-risk situations.
| Task | Frequency | Standard / Target |
|---|---|---|
| Hot water temperature — calorifier | Monthly | ≥ 60°C stored |
| Hot water temperature — sentinel outlets | Monthly | ≥ 50°C within 1 minute |
| Cold water temperature — sentinel outlets | Monthly | < 20°C within 2 minutes |
| Flush unused outlets | Weekly | Run for minimum 2 minutes |
| Legionella water sampling | Quarterly | < 100 CFU/litre |
| TMV maintenance and check | 6 – 12 monthly | Manufacturer's specification |
| [Water tank inspection and clean](/services/water-tank-cleaning) | Annually | Visual, with photographic record |
| Full risk assessment review | Every 2 years | By competent person |
Common Compliance Failures
After years of conducting assessments across London, these are the most frequent compliance failures we encounter. Any of these gaps could result in enforcement action during an HSE inspection.
- •No written risk assessment — or one that has never been reviewed since initial assessment
- •No temperature monitoring records — monitoring may be happening but isn't documented
- •Water storage tanks not inspected or cleaned — the single most common physical failing
- •Dead legs and unused pipework not removed or managed — often from past refurbishment
- •No responsible person formally appointed — no one has clear ownership of the programme
- •Infrequently used outlets not flushed — common in buildings with spare rooms, vacant units, or seasonal spaces
Getting and Staying Compliant
Compliance doesn't need to be complicated or expensive. Start by appointing a competent water treatment specialist to carry out your risk assessment and implement the recommended control measures. Establish a routine monitoring schedule, keep thorough records, and review your arrangements whenever there are changes. The cost of maintaining compliance is a fraction of the cost of dealing with an enforcement notice, a contamination event, or — worst case — a case of Legionnaires' disease traced back to your building.