If you have ever been interested in what Legionella is, you know how serious encountering it is. This bacteria is extremely dangerous and might be fatal if digested. It lives inside water systems that are not maintained properly, which is why you must be aware of, and follow the Legionella Written Scheme of Control.
What is Actually a Legionella Written Scheme of Control?
Everyone must be aware of the Legionella Written Scheme of Control as this is the detailed instruction list for keeping the water systems safe from this dangerous bacteria. It outlines the roles and responsibilities of everyone involved in the process: the staff, users, and the detailed control measures to be implemented.
Jargon Used can Vary
Terminology among organisations may vary. Encountering different names for the same procedure means the same process must be used, regardless of the different jargon. The language might shift, but the purpose is the same: ensuring water hygiene and protection against Legionella.

Why Should You Have a Written Scheme of Control for Legionella?
A written scheme is not optional; it is a legal obligation. Failure to implement and maintain one could lead to serious health risks, including outbreaks of Legionnaires’ disease, as well as regulatory consequences. Having a clear scheme demonstrates that the necessary measures have been put in place to control Legionella and that the duty holder is meeting their obligations.
Creating a Legionella Control Scheme
Designing an effective scheme requires a full Legionella risk assessment to identify hazards and set out measures required to reduce risk. This should involve specifying control methods, detailing responsibilities, and ensuring regular monitoring. Implementation must be thorough, supported by technical guidance, and regularly reviewed to ensure ongoing compliance and effectiveness.
Key elements of a written scheme of control include:
- Identification of responsible personnel for monitoring and maintenance
- Operational guidelines for system use and maintenance
- Precautionary measures, such as chemical treatments and inspections
- Scheduled checks and tests, including their frequency such as temperature checks, sampling, TMV servicing and more.
- This document should be regularly reviewed and updated as necessary to reflect any changes in the water system or new risks that are identified.
Difference Between a Legionella Risk Assessment and a Legionella Written Scheme of Control
The first one is basically identifying the risk when it comes to Legionella, while the second is the framework required for protecting the organisation from it. To use the scheme, you must perform the assessment first. Both properly done together assure perfect safety and protection against dangerous bacteria.

Relevant Legionella Legislation, Codes of Practice & Guidance
The Written Scheme of Control must align with applicable regulations and technical guidance. The following are key documents:
HSE ACOP L8
ACOP L8 is the main guidance from the Health and Safety Executive. It sets out what the law requires and how duty holders should meet those requirements.
HSG274 Legionnaires’ Disease: Parts 1, 2, and 3
HSG274 gives detailed advice on how to manage specific systems, from cooling towers to hot and cold water. It supports ACOP L8 with practical instructions.
Department of Health: Health Technical Memorandum (HTM) 04-01
This memorandum applies to healthcare premises. It sets out how to maintain safe water systems in hospitals and clinics, where vulnerable people are most at risk.
Department of Health: Health Technical Memorandum (HTM) 01-05
This guidance covers dental practices and other clinical settings. It ensures water systems meet hygiene standards needed to protect staff and patients.
BS 7592:2022
BS 7592 describes how to take water samples for Legionella testing. Following this standard ensures testing is carried out correctly and results are reliable.
BS 8580:2019
BS 8580 offers guidance on conducting a Legionella risk assessment. It ensures assessments are carried out thoroughly and consistently across different water systems.
Legionella Control Association
The Legionella Control Association provides a code of conduct for organisations delivering water hygiene services. Membership demonstrates a commitment to best practice and compliance.
Expert Legionella Risk Management with Comfort Services Group
Comfort Services Group provides comprehensive support for managing Legionella risks. From risk assessment through to implementing and reviewing written schemes of control, their expert approach ensures compliance, effective control measures, and peace of mind for duty holders.
FAQs
Should I have a digital Legionella Written Scheme of Control?
Most definitely. The scheme gives you a clear guideline of what must be done to prevent the formation and growth of Legionnela inside the water system. It’s the best way to control the environment and prevent diseases.
Is every property required by law to have a written scheme in place for preventing and controlling the risk of Legionella?
Duty holders are required to have it by law, but not every property. Most workplaces require one, especially healthcare facilities, food industry organisations, and others.
How can I properly review my Legionella Written Scheme of Control?
It is best to hire a professional who will review it. In general, this must be done when changes occur within the water system or particular changes are applied to the system. Every modification requires a review of the scheme, but regular reviews although nothing was changed, are also recommended.
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