Who should arrange water chlorination for a commercial water system?

The dutyholder for the commercial premises should arrange water chlorination. In practice, this is usually the organisation or individual with control of the water system, such as a building owner, employer, landlord, managing agent or facilities team. They may delegate the practical arrangements to a competent water hygiene contractor, but delegation does not remove the need to define responsibility, authorise the work and retain evidence that the treatment was properly managed.

Responsibility can be less straightforward where several organisations occupy or manage the same building. A lease, facilities management agreement or service contract may allocate day-to-day water system duties to a tenant, managing agent or maintenance provider. Those arrangements should identify who is responsible for:

• maintaining the system and its schematic information;
• commissioning risk assessments and deciding whether chlorination is necessary;
• appointing a suitably competent specialist;
• co-ordinating access, isolation and communication with building users;
• reviewing the treatment results and dealing with any further work.

Where responsibilities are shared, each party should understand the boundary between its own system and any communal or landlord-controlled installation. A written agreement is preferable to an assumption that the facilities manager, plumber or tenant is automatically responsible. The person arranging the work should also confirm who will receive the treatment report and who will act on any unsatisfactory findings.

When should the responsible organisation arrange chlorination? Chlorination may form part of the commissioning process for a new or substantially altered installation. It can also be required following remedial work, contamination, prolonged stagnation or a finding that indicates the system needs disinfection. The decision should be based on the water hygiene risk assessment, the system’s condition and the advice of a competent specialist rather than on a standard treatment schedule applied without investigation.

A positive microbiological result does not, by itself, mean that the person who receives the report should immediately dose or disinfect the system. The result needs to be considered alongside the system design, operating conditions, sampling method, temperature control, history and potential exposure of users. The responsible person should obtain a clear recommendation explaining what treatment is proposed, why it is appropriate and whether underlying defects need correcting.

The person arranging the work should appoint a competent contractor. Competence involves more than being able to introduce chlorine into pipework. The contractor should be able to assess the installation, select a suitable disinfection method, calculate and control the treatment, protect users and materials, and verify that the system can be returned to service safely. They should also understand the additional controls needed where the system supplies drinking water or serves vulnerable occupants.

Before work starts, the responsible organisation should expect a defined method statement and agree practical controls. These commonly include:

• identifying the sections of system to be treated and any parts that cannot be included;
• isolating the supply and preventing unauthorised use during treatment;
• protecting occupants, staff, contractors and sensitive equipment;
• checking the suitability of the pipework, tanks, fittings and associated components;
• controlling chemical handling, storage, dosing and discharge;
• planning flushing and reinstatement of the supply;
• arranging sampling or other verification before normal use resumes.

The building owner or other dutyholder should ensure that users receive suitable information about the interruption, restrictions on use and any required flushing or reinstatement arrangements. This is particularly important in premises where water is used for drinking, food preparation, healthcare activities, personal washing or other purposes where poor control could expose people to risk.

Facilities and maintenance teams often coordinate the work, but they should not be expected to make unsupported technical decisions. Their role may include providing drawings, asset information, access and isolation details, checking that the contractor can work safely on site and co-ordinating other trades. The technical scope, treatment parameters and interpretation of verification results should come from a person with appropriate water hygiene competence.

After treatment, the responsible person should receive and retain records showing what was done and whether the system was suitable for return to service. Useful documentation may include the treated areas, date of work, method used, chemical and control records, flushing information, sample results, restrictions applied and any recommendations for follow-up action. These records should be considered alongside the water hygiene risk assessment and ongoing monitoring arrangements, not filed without review.

Blue Fish Water Management can support organisations by advising on the need for chlorination, assessing the proposed scope and providing related water hygiene services such as risk assessment, testing, compliance review and system monitoring. The appropriate arrangement depends on who controls the system, why treatment is being considered and the risks identified at the premises.