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UK Water Quality Law (inc Legionnaires’ Disease)


Health & Safety at Work Act 1974

The Health & Safety at Work Act 1974 is an enabling Act allowing Regulations to be made under it.

The Regulations are the initial stage in increasing the detailed legislative requirements, but even so the law is becoming less prescriptive, and the “reasonable measures” that need to be taken are being left to the employer to decide.  It is the primary piece of legislation covering occupational health and safety in Great Britain. This decision making process is known as risk assessment and the control measures to be adopted should be proportionate with the risk involved in the activity.


The Water Industry Act 1991

Similarly, The Water Industry Act 1991 is an enabling Act allowing Regulations to be made under it. For example, Clause 67 of the act allows the Secretary of State to proscribe Standards of wholesomeness for water, prescribing the purposes for which the water is to be suitable, substances that are to be present or absent and the concentrations.

However, if not stated directly by law there is much guidance that may, (or must – depending on the circumstances) be followed, thPrimary legislation refers to Acts of Parliament, below this comes secondary legislation which incudes statutory instruments made under Acts of Parliament (orders, rules, and regulations) and finally Guidance Material.e hierarchy of which is shown below.

Acts of Parliament

(is a statute, commonly called a law, enacted as primary legislation)


(approved by Parliament and have the force of the law)

Approved Codes of Practice

(sets out requirements in more detail than the Regulations themselves)

  • Legionnaires’ disease – The control of legionella bacteria in water systems (L8)

Guidance/Other Literature

  • HSG274 Parts 1-3 The control of legionella bacteria in evaporative cooling systems\hot & cold water systems\other risk systems
  • HSG282 Control of legionella and other infectious agents in spa-pool systems
  • BS EN 806 Parts 1-5 Specifications for installations inside buildings conveying water for human consumption
  • BS EN 1717:2001 Protection against pollution of potable water in water installations
  • NHS Model Engineering Specification – DO8 (Thermostatic Mixing Valves)
  • W.H.O Legionella and The Prevention Of Legionellosis
  • HTM 04-01: The control of Legionella, hygiene, “safe” hot water, cold water and drinking water systems
  • Swimming pool water: Treatment and quality standards – Pool Water Treatment Advisory Group
  • The Institute of Plumbing: Plumbing engineering services design guide
  • Hygiene for spa pools – Public Health Laboratory Service

HSE Legionnaires’ disease

The control of legionella bacteria in water systems. Approved Code of Practice and guidance (L8)

The Health and Safety Executive’s Approved Code of Practice and Guidance document titled “Legionnaires’ disease: The control of legionella bacteria in water systems” (L8) gives practical advice on how to comply with UK health and safety law with respect to the control of Legionella bacteria.

This Code is important in that it has a special legal status. Following the guidance is not compulsory and you are free to take other action. But if you do follow the guidance you will normally be doing enough to comply with the law. Health and safety inspectors seek to secure compliance with the law and may refer to this guidance as illustrating good practice.

If you are prosecuted for a breach of health and safety law, and it is proved that you did not follow the relevant provisions of the Code, you would need to demonstrate that you have complied with the law in some other way or a Court would find you at fault.

Prosecutions would be sought for non-compliance with:-

  • Health and Safety at Work etc. Act 1974 (sections 2, 3, 4 and 6)
  • Control of Substances Hazardous to Health Regulations 1999 (regulations 6, 7, 8, 9 and 12)


Author: Duncan Hollis