The Importance of an Accurate and Accessible Written Control Scheme

A written control scheme is the foundation of any effective Legionella control programme. It sets out exactly how risks are managed, by whom, and how often. Under HSG274 Part 2, every duty holder must ensure that a clear, up-to-date, and auditable control scheme is in place.

Think of your written control scheme as the instruction manual for your building's water systems. Without it, there's no reliable way to ensure that maintenance, monitoring, and corrective actions are carried out consistently and effectively.

What is a Written Control Scheme?

A written control scheme details the specific actions required to manage Legionella risk within a building's water systems. It should describe the system layout, identify the responsible persons, and set out control measures and monitoring procedures in line with HSG274 Part 2 and L8 Approved Code of Practice (ACoP) requirements.

At a minimum, the control scheme should include:

• A clear description of each hot and cold water system and any associated plant or equipment.

• Control measures to prevent or reduce Legionella growth, such as temperature control, flushing, cleaning, and chemical dosing.

• Roles and responsibilities, identifying the responsible person and duty holder.

• Schedules for routine checks, maintenance, and sampling.

• Procedures for corrective action if control parameters are not met.

This document ensures that everyone involved in Legionella control understands their duties and the steps needed to maintain compliance.

Why Accuracy and Detail Matter

An effective control scheme must be accurate, detailed, and tailored to the specific building. Generic or outdated documents can lead to gaps in management and missed risks.

Inaccurate or incomplete control schemes can result in:

• Confusion among staff about their responsibilities or correct procedures.

• Inconsistent monitoring and missed checks.

• Regulatory non-compliance, leading to enforcement action.

• Increased risk of Legionella growth and potential outbreaks.

Regular review and updates are crucial — especially following any system modification, building use change, or audit findings. The control scheme must reflect the current operational reality, not just a historical version of the system.

Auditability and the Role of Accessible Records

HSG274 Part 2 stresses that Legionella control schemes must be auditable. This means all actions, monitoring, and control measures must be clearly documented and traceable. If an inspector or auditor requests evidence, you should be able to demonstrate — quickly and clearly — that all procedures are being followed as written.

Accessibility is key. A control scheme that's buried in a filing cabinet or scattered across spreadsheets is of little value when it comes to compliance or crisis response. Using a digital Legionella logbook allows for real-time updates, centralised document control, and instant access for all authorised personnel.

With a digital system such as Legionella Logbook, you can:

• Maintain a live, auditable record of your written control scheme.

• Share documents instantly with site teams or auditors.

• Record evidence of tasks, temperatures, and sampling results in one secure platform.

• Simplify compliance reporting and demonstrate due diligence.

Your Control Scheme: The Instruction Manual for Compliance

Just as an instruction manual ensures equipment runs safely and efficiently, a written control scheme ensures your Legionella control regime functions as intended. It provides structure, accountability, and clarity — all essential for maintaining compliance and protecting health.

Without a reliable, up-to-date control scheme, even the most sophisticated monitoring programme can fail. Accuracy, auditability, and accessibility together form the foundation of effective Legionella management.

Your written control scheme is the roadmap for Legionella control — guiding every inspection, flush, and sample. Treat it as a living document that evolves with your building and your systems. By keeping it accurate, auditable, and easily accessible, you ensure not only compliance with HSG274 Part 2 but also the continued safety of building users.