Who should arrange mains chlorination for a new water main?

Responsibility normally rests with the organisation commissioning and controlling the new main, although the contract may allocate the practical arrangements to a principal contractor, utilities contractor or specialist water hygiene company. The responsible party must make sure that chlorination, post-treatment sampling and acceptance are completed before the main is put into service or connected to the wider supply system.

Typical responsibilities are divided as follows:

• Developer or client: sets the project requirement, confirms who is responsible under the contract and ensures that suitable budget and time are allowed for cleaning, disinfection, sampling and any corrective work.
• Principal contractor: coordinates the activity where it forms part of a larger construction project. This includes confirming that the main has been installed in a condition suitable for disinfection, controlling access to the work area and coordinating the specialist, commissioning team and water undertaker.
• Utilities or main-laying contractor: provides installation details, arranges access to valves and fittings, and rectifies defects or contamination arising from the construction work. Their involvement does not necessarily transfer overall compliance responsibility from the client or developer.
• Water hygiene specialist: prepares or follows the appropriate method, carries out the disinfection safely, takes or arranges the required samples and reports the findings. The specialist should understand the relevant water undertaker's submission and acceptance requirements.
• Water undertaker: may set conditions for connection, witnessing, sampling, documentation and approval, particularly where the main will become part of an adopted network. Its requirements should be confirmed before work is programmed.

Where the new main is installed on a development, the developer should establish responsibility at the design and procurement stage rather than leaving it to the final commissioning period. Tender documents and work packages should state who will arrange chlorination, who will provide water and discharge points, who will liaise with the undertaker, and who will deal with an unsatisfactory result. Clear allocation prevents the common problem of an installed main being ready physically but unable to enter service because the required evidence has not been accepted.

The party arranging the work should also check that the proposed specialist is competent for mains disinfection and independent enough to report the result objectively. Sampling should be undertaken in accordance with the agreed procedure, using a suitable laboratory where laboratory analysis is required. A certificate or report should identify the section tested, the method used, sampling details, results and any limitations relevant to acceptance.

Responsibility can differ where the water undertaker installs or directly commissions the main, or where an existing private system is being transferred into another party's control. In those circumstances, the written adoption, connection or construction agreement should be treated as the starting point. If it does not clearly identify the duty holder, the client or developer should obtain clarification from the undertaker and the project team before commissioning work.

Blue Fish Water Management can advise on the scope of the disinfection, sampling and certification needed for a new main, helping clients and contractors define responsibilities and address compliance requirements before commissioning. Its water hygiene specialists can also provide UKAS-accredited water testing where this forms part of the agreed project requirements.