Chlorination Services and Certificates

We provide professional chlorination services for new installations, altered pipework and existing water systems that require disinfection. Each treatment is planned around the system in question and completed using controlled chemical dosing, contact-time monitoring and thorough flushing.

Our services are suitable for builders, developers, property managers, commercial clients and homeowners. Where required, we can also arrange water sampling and testing through a UKAS-accredited laboratory before issuing the relevant chlorination documentation.

Chlorination is a measured process. The system is filled and dosed to a set concentration, the solution is held against the internal surfaces for a specified contact period so it reaches every part of the treated section, and the system is then flushed until the residual returns to the normal level of the incoming supply. A sample is taken where required so the result is confirmed by laboratory analysis rather than left to assumption.

New pipework is not clean by default. Cut ends, jointing compounds, dust, debris, and standing water left during installation all provide bacteria with a place to establish. Existing systems can also need treatment after alteration, repair, a period of standing water, or an unsatisfactory sample. Chlorination addresses these conditions in a controlled way, section by section, with the concentration checked at outlets around the system during the works.

Chlorination is normally arranged when a water system has been installed, opened up, left standing, or shown a problem. The common circumstances are set out below.

Newly installed pipework. Any new distribution system is disinfected before it is put into service. This applies to single dwellings, extensions, and multi-unit schemes alike. The certificate normally forms part of the handover file.

A new mains connection. New supply pipework generally has to be disinfected, flushed, sampled and documented before the connection is approved. Where a water authority asks for evidence, the chlorination certificate and the laboratory report together provide it. Arranging the work before the connection date keeps the programme on schedule.

Refurbishment and alterations. Extending, rerouting or replacing pipework opens the system up, so the affected section is disinfected again before handover. This applies whether the alteration is a single branch or a full refit.

Repairs that expose the inside of the pipe. Any repair that opens a pipe, fitting or tank creates a route for contamination. The exposed section is treated before the system returns to normal use.

An unsatisfactory water sample. Where laboratory analysis comes back unsatisfactory, chlorination is the usual remedial step before resampling. The cause is considered first, so the resample tests a system that has been properly addressed rather than simply retested.

Buildings brought back into use. Water left standing in an empty or lightly used building should be treated as suspect before residents or staff return. Flushing is checked first, and chlorination follows where the condition of the system calls for it.

Ongoing compliance. Care homes, schools, healthcare settings and food premises are commonly asked for current certification. A dated certificate with the laboratory analysis attached provides the record.

We carry out four related types of chlorination. Each one ends with flushing, and with sampling and documentation where required.

Mains chlorination. Treatment of the supply pipe between the connection point and the building. The new main is filled and dosed, held for the contact period with the concentration monitored along its length, flushed back to background level, and sampled. This is the disinfection a water authority asks about when a connection is held pending a certificate.

New pipework chlorination. Disinfection at the end of the commissioning sequence for new or extended distribution pipework. The pipework is flushed first to clear debris and standing water left from installation, then the network is dosed, held, flushed and sampled. Booking this stage early keeps handover on schedule.

Tank chlorination. Disinfection of cold water storage tanks alongside the pipework they feed, usually as the last stage of a tank clean. The tank is drained and physically cleaned first, because disinfectant cannot act reliably through sediment or scale. Our water tank cleaning page describes the cleaning stage in full.

Remedial chlorination. Treatment following a failed sample, a period of stagnation, a contamination concern, or a finding raised by a Legionnaires’ assessment. The method is the same controlled sequence, with added attention to the cause, so the follow-up sample tests a system that has been corrected.

Where pipework alone is the concern, our pipework disinfection service covers flushing and disinfection of new, altered or existing pipework. Where laboratory confirmation is the main requirement, see water testing and sampling.

Our chlorination and disinfection work is carried out with reference to the requirements and guidance relevant to each water system, including:

These documents are named so they can be checked. The certificate for each job records the method and the standard followed, so the record shows which procedure the work was carried out against.

You receive a written report setting out the system as found, the conditions identified, and the reasoning behind each finding. Findings are categorised so it is clear what needs attention now and what can be planned in. The report is accompanied by a prioritised list of recommended actions and monitoring, and a statement of the level of risk identified for the compliance file.

The written report describes the system, the risks found and the basis for each finding. The recommendations cover maintenance, remedial work or monitoring as appropriate. On a low-risk system the report may confirm that no further action is required beyond the existing controls.

The report alone does not discharge the duty. That is done by acting on the findings, keeping the records, and reviewing the assessment when the system or its use changes. Records, including the assessment, monitoring entries, sample results and remedial work, belong together in the water safety file, where a managing agent, insurer or enforcing officer can be shown them.