Who is responsible for arranging potable water chlorination?

Responsibility for potable water chlorination should be assigned to the organisation controlling the water system or commissioning the relevant works. In a new build, refurbishment or installation project, this is usually the client, building owner or developer. The contract may pass the practical task to a principal contractor, mechanical contractor or project manager, but the commissioning organisation should confirm who is accountable and what evidence must be supplied.

Responsibility is often shared between several parties, each with a different role:

• Building owner, client or developer: commissions the work, approves the scope and retains overall control of the project requirement.
• Principal contractor or project manager: coordinates the chlorination activity with other construction and commissioning tasks where this has been included in the project arrangements.
• Designer or water-system engineer: identifies system characteristics that affect the treatment method, including materials, storage arrangements, circulation and access for sampling.
• Installer or mechanical contractor: completes the installation in accordance with the design, provides information about the system and rectifies defects that could affect disinfection.
• Competent water hygiene provider: develops or follows the treatment procedure, carries out the work safely, takes or arranges appropriate samples and produces the relevant records.
• Facilities or estates team: takes responsibility for the system after handover, including retaining documentation, managing follow-up actions and incorporating the installation into ongoing water hygiene arrangements.

The party arranging the work should not assume that commissioning a chlorination exercise transfers every duty to the specialist provider. The organisation in control still needs to make sure that the system is accessible, isolated where necessary, correctly identified and safe for treatment. It should also ensure that any people using the premises are protected from exposure to disinfectant and that the system is not returned to service until the required checks have been completed.

On construction projects, responsibility should be settled before practical completion rather than left as an informal assumption. The project documents can state who will:

• confirm the sections of pipework, tanks and outlets included in the treatment;
• provide drawings, commissioning information and details of installed materials;
• coordinate the work with the water undertaker, building operator and other contractors where relevant;
• arrange sampling and assess the resulting reports;
• manage failed samples, leaks, dead legs or other remedial issues; and
• compile the handover file for the person who will operate the building.

For an occupied building, the responsible person is generally the owner, employer, landlord, managing agent or facilities operator with control of the water system. A legionella risk assessment may identify circumstances in which disinfection is appropriate, such as alterations, contamination, prolonged stagnation or remedial work. The decision should be based on the condition and use of the system, not on a routine assumption that every installation needs the same treatment.

A water undertaker may have a role where its approval, connection requirements or operational controls are relevant, but it is not normally the party that arranges chlorination of a customer's private internal installation. The organisation commissioning the installation should establish any notification, isolation or acceptance requirements that apply to the particular project.

Before appointing a provider, the responsible organisation should define the intended outcome and request documentation that demonstrates how it will be achieved. Useful records include the treatment method, areas covered, chemical and contact details, safety controls, sampling plan, laboratory results, dates, locations and any outstanding actions. These records help the building operator demonstrate appropriate management during handover, audits or future investigations.

Blue Fish Water Management can support organisations by reviewing the project or existing system information, advising on the appropriate water hygiene arrangements, coordinating potable water treatment and arranging suitable testing and documentation. The commissioning organisation remains responsible for deciding who has control of the system and ensuring that the agreed actions are completed.