There is a common assumption that once you appoint a competent designer or installer for a new water system, the legal burden for getting it right sits entirely with them, or that once the job is signed off the duty bounces back to you alone. Neither is correct. Appointing a contractor does not transfer the whole duty, and it does not absolve the supply chain either. Section 6 of the Health and Safety at Work etc. Act 1974 places its own, separate legal duties on those who design, manufacture, import, supply and install articles for use at work [1]. Water plant and the components within it fall squarely inside that definition. Responsibility is shared.
This matters because most Legionella risk is built in, not bolted on. A dead leg specified on a drawing, a calorifier that cannot reach a safe storage temperature, or a material that sheds nutrients into potable water will sit in the fabric of the building for decades. Catching those problems at design and commissioning is cheaper and safer than chasing them through years of remedial flushing and sampling. This article explains what section 6 requires of the supply chain, and what you, as the duty holder commissioning the work, can and should demand from them.
This is general guidance on health and safety duties, not legal advice. For a decision with legal consequences, take advice on your specific circumstances.
What section 6 actually places on the supply chain
Section 6 of HSWA sets duties on anyone who designs, manufactures, imports or supplies an article for use at work. In broad terms it requires them, so far as is reasonably practicable, to ensure the article is designed and constructed to be safe and without risks to health when properly used, to carry out or arrange any necessary testing and examination, and to provide adequate information about the use for which it was designed and any conditions necessary to ensure it will be safe and without risks to health [1]. There is a parallel duty on those who erect or install to ensure nothing about the way the article is installed makes it unsafe [1].
The ACoP L8 carries this through into the water-systems world. It sets out responsibilities for designers, manufacturers, importers, suppliers and installers, and reinforces the duty to provide adequate information about the safe use of what they supply [2]. HSG274 Part 2 then describes the design and commissioning expectations that the supply chain should support, including designing out conditions that favour Legionella growth and handing over a system that can be operated and maintained safely [3].
Put plainly: the people who put the system together owe a duty to make it safe by design and to tell you how to keep it safe. You are entitled to that information, and you need it to discharge your own operational duties.
Where the duty-holder duty starts and stops
Section 6 covers the article and the information about it. It does not cover how you run the system once it is in your hands. The day-to-day duties, the written scheme, monitoring, temperature control, record keeping and acting on results, remain with the duty holder and the appointed responsible person. The two sets of duties run alongside each other rather than replacing one another.
So the practical division looks like this. The supply chain is responsible for a safe design, suitable materials and components, proper testing, and clear information on safe use and maintenance. You are responsible for operating within those instructions, keeping the risk assessment current, and managing the system through its life. If you want to understand how the operational side is structured, see duty holder and responsible person roles in Legionella management. Where contractors carry out ongoing work for you, the boundaries are best fixed in writing, as covered in working with contractors to ensure Legionella compliance.
Why you should demand the information, not just hope for it
The duty to provide information is only useful if you collect it and use it. Operation and maintenance manuals, commissioning records and material certificates are not paperwork for the file. They tell your responsible person what the safe storage and distribution temperatures are, where the sentinel points sit, which materials are in contact with the water, and how the system was designed to behave. Without them, the first risk assessment is guesswork and any later defect is far harder to attribute.
Make the information a condition of the contract and of sign-off. Withholding final payment until a complete handover pack is delivered is a legitimate and common commercial lever. The handover pack should feed directly into your water safety plan, so that what the supply chain designed and what you operate are the same system. See developing a comprehensive water safety plan for how that information is structured and maintained.
Field checklist: what to require from the supply chain
Use this as a specification and acceptance checklist across the three stages. Adapt it to the scale of the work.
At design stage
- A design that demonstrably avoids dead legs and minimises low-flow and dead-end pipework
- Stored and distributed water able to hold recognised safe temperatures, with calorifiers and pipework sized accordingly [3]
- Materials and fittings in contact with potable water shown to be suitable and water-fittings compliant
- Tanks, calorifiers and outlets located and configured for inspection, draining and sampling [3]
- A design risk assessment or hazard review identifying residual Legionella risks for the operator to manage
At manufacture and supply stage
- Confirmation that plant and components are fit for the supplied duty and tested as required [1]
- Material and product certificates for items in contact with the water
- Written information on safe installation, use, operating limits and maintenance [1][2]
- Clear marking of safe operating conditions, for example temperature set points and limits
At installation and commissioning stage
- Installation that does not introduce dead legs, cross-connections or contamination [1]
- Pre-commission cleaning, flushing and, where specified, disinfection records [3]
- Commissioning records confirming temperatures and flow achieved at representative outlets
- A complete operation and maintenance manual and asset register handed over
- As-installed drawings reflecting what was actually built, not just what was drawn
Myth and reality on shared responsibility
The persistent myth is that buying in expertise moves the legal risk off your desk. The reality under section 6 is more balanced and, for a careful duty holder, more reassuring. The supply chain carries genuine, enforceable duties to design safe systems and to inform you. You carry the duty to operate them safely. When something goes wrong, the relevant question is not who to blame in the abstract but which duty was breached and by whom. That is why the handover information matters so much: it is the record of what the supply chain designed for and instructed, against which both your operation and any defect can be judged.
Frequently asked questions
Does HSWA section 6 move the Legionella duty away from me?
No. Section 6 places additional duties on the supply chain; it does not lift your operational duties as a duty holder [1]. The two run in parallel. The supply chain is responsible for safe design, suitable plant and adequate information on safe use, while you remain responsible for operating, monitoring and maintaining the system once it is in service [2].
What information can I demand from a manufacturer or installer?
You can reasonably require adequate information about safe installation, use, operating limits and maintenance, which is part of their section 6 duty [1][2]. In practice that means operation and maintenance manuals, commissioning and pre-commission cleaning records, material and product certificates for items in contact with potable water, and as-installed drawings. Make a complete handover pack a condition of sign-off.
Does this apply to a small TMV or tap replacement?
The principle still applies, because section 6 covers articles for use at work regardless of size [1]. For a minor component the information may be a product data sheet and fitting instructions rather than a full manual, but the duty to supply something suitable and to inform on safe use does not disappear. Keep the documentation and update your records and risk assessment to reflect the change.
What if the installed system has a design flaw?
A design or installation defect may engage the supply chain’s duties under section 6, particularly where it was not safe when properly used [1]. Document the issue, raise it with the responsible party, and in the meantime manage the residual risk operationally, for example through control measures recorded in your risk assessment [3]. This is general guidance, not legal advice; for a contractual or liability dispute take specific professional advice.
Sources
- HSE, Health and Safety at Work etc. Act 1974, section 6: duties of those who design, manufacture, import or supply articles for use at work. https://www.legislation.gov.uk/ukpga/1974/37/contents
- HSE, Approved Code of Practice and guidance L8 (2013), Responsibilities of designers, manufacturers, importers, suppliers and installers, p.20. https://www.hse.gov.uk/pubns/books/l8.htm
- HSE, HSG274 Part 2: design and commissioning expectations that the supply chain should support. https://www.hse.gov.uk/pubns/books/hsg274.htm