Private Water Supply Corrective Action Log

What a corrective-action log is — and is not

A corrective-action log is an operator's working record of a problem and what happened next. It can connect a failed result, alarm, inspection finding, complaint, maintenance defect, notice or supply interruption to the person responsible, the interim controls, the work completed and the evidence used to close the action.

That is valuable, but it is important to use the right language. The Private Water Supplies (England) Regulations 2016 do not create a specific statutory operator document called a “corrective action log”. The local authority is the regulator. Its statutory records, investigations, risk assessments, information duties and notices are separate from your own operational workflow.

This separation matters because ticking an internal action as complete does not revoke a Regulation 18 notice, prove that the supply is wholesome or replace any evidence the local authority requires.

The legal framework after a problem

For England, DWI's current Regulation 16 guidance says the local authority must investigate where it suspects, for any reason, that a private water supply is unwholesome, or where an indicator parameter does not meet the prescribed value. The purpose is to establish the cause so that the correct next step can be determined.

If the local authority suspects a potential danger to human health, Regulation 15 requires prompt steps to ensure people likely to consume the water are informed, told the nature of the danger where possible, and given advice to minimise the danger. If the investigation establishes circumstances requiring a health-risk notice, Regulation 18 is the relevant notice provision.

These are regulator duties. An owner, occupier or other person with management or control can nevertheless be a relevant person and may be required to provide information, carry out remedial work or comply with a notice. That is why a disciplined operator record is useful: it helps you show exactly what was known, what was requested, who acted and what evidence exists.

Regulations 15–21: what each one actually does

The numbering is easy to get wrong. In the current England Regulations, the sequence is:

Types of problem and example actions

A good corrective-action record should describe the actual problem rather than applying the same template to every incident. Examples include:

Microbiological failure

Record the result, parameter, sample point, date, authority/laboratory contacts, any restrictions or consumer advice issued by the authority, investigatory sampling, source-to-tap inspection findings and the identified cause. Corrective work may involve source protection, cleaning, treatment repair, disinfection or distribution work, but the appropriate response depends on the investigation. Do not assume “fit UV” or “boil the water” is automatically the correct permanent answer.

Chemical failure

Record the parameter, concentration, history/trend and suspected source. A serious chemical result can require very different protection from a microbiological failure. Follow local-authority and UKHSA advice rather than applying a generic restriction. If Regulation 17 authorisation is discussed, remember that it is limited to the statutory conditions and cannot be used where it would create a potential danger to health.

UV, filtration or disinfection failure

An alarm, lamp failure, fouled sleeve, filter bypass, exhausted media, dosing fault or loss of power is an operational finding. Record the affected equipment, alarm or observation, duration if known, water use during the event, immediate control, contractor/manufacturer advice and repair evidence. If water quality may have been compromised, the incident may also justify authority contact and investigation rather than being treated as a maintenance-only task.

Storage or distribution contamination

Record tank defects, ingress, uncovered vents, stagnation, dead legs, bursts, cross-connections, pressure loss or contamination introduced through pipework. Include the exact area and consumers affected, because the regulatory response can depend on whether the cause is within a domestic distribution system and whether the water is made available to the public.

Source contamination or weather-related event

Heavy rain, flooding, slurry or pesticide incidents, damaged spring chambers, borehole-head defects and changes in raw-water quality can alter risk rapidly. Capture weather/event dates, photographs, source condition, raw-water observations, treatment performance and any temporary arrangements. This evidence can be important when the local authority reviews the Regulation 6 risk assessment.

Repeat or recurring failure

Do not create isolated records that hide the pattern. Link the new action to earlier failures, previous repairs and follow-up results. Recurrence can show that a temporary fix did not address the root cause or that an existing control is unreliable.

What to record for each corrective action

The purpose of the log is traceability. A useful record usually includes:

• Trigger: laboratory result, risk-assessment finding, notice, complaint, alarm, inspection, maintenance defect or incident.
• Affected supply and location: supply name, source/treatment asset, sample point, building or distribution zone.
• Date and time: when the problem was identified and, if known, when it began.
• Problem description: factual wording, including parameter/result or equipment condition where relevant.
• Immediate controls: only the controls actually implemented and the basis for them — for example local-authority advice, manufacturer instruction or professional recommendation.
• People informed: local authority, laboratory, users/consumers, contractor, owner, manager or other relevant person, with dates.
• Investigation: inspections, samples, measurements, evidence reviewed and root cause once established.
• Permanent corrective work: exactly what was repaired, replaced, cleaned, isolated, redesigned or changed.
• Evidence: photographs, invoices, service reports, certificates, laboratory results, updated procedures, correspondence or notice documents.
• Follow-up: further sampling, inspection or monitoring and what it demonstrated.
• Risk-assessment link: whether the local authority reviewed or updated its assessment, or whether a material change should be raised with it.
• Closure: who closed the operator action and why. For a statutory notice, separately record authority confirmation, amendment or revocation where applicable.

Investigation, repeat testing and follow-up

DWI is explicit that simply resampling at the original point to obtain a different result does not amount to the Regulation 16 investigation. The investigation should be risk based and can include site inspection and samples at different points such as source, collection chamber, storage, before and after treatment, and consumer outlets where appropriate.

Repeat testing can still be important. DWI's monitoring guidance says additional repeat testing may be required to help determine the cause and extent of a failure. The distinction is that sampling is evidence within the investigation, not a substitute for finding the cause.

Where reduced monitoring frequency had been permitted for a parameter and that parameter breaches its regulatory value, DWI's Regulation 16 guidance says monitoring frequency must return to normal following the breach. Your operator log should therefore capture any revised monitoring programme communicated by the authority instead of assuming the old reduced schedule still applies.

Closure should be evidence-led. For treatment work, this may mean service/commissioning evidence plus the follow-up requested by the local authority. For structural repairs it may include photographs or contractor documents. For a health-risk notice, only the local authority can amend or revoke the notice; the operator log should mirror that status rather than self-declare regulatory closure.

Feed findings back into Regulation 6 risk assessment

For supplies within Regulation 6 scope, the statutory risk assessment is the local authority's responsibility. DWI says the assessment should be reviewed when it is inadequate or circumstances change significantly. Its current Regulation 16 investigation note also says the investigation should consider changes since the last risk assessment, while the Regulation 18 notice guidance tells the local authority to update the risk assessment when investigating a potential health danger.

That creates a useful feedback loop: problem → investigation → cause → corrective work → verification → risk-assessment review where needed. Your records support the loop by preserving facts the authority may need: asset failures, source changes, weather patterns, repeat incidents, treatment limitations and evidence that work was completed.

Do not edit your own copy of a council risk assessment and treat that as the statutory review. Instead, keep the operational evidence current and raise significant changes or failures with the authority.

Urgent protection versus routine corrective work

Not every corrective action is an emergency. A maintenance observation such as early filter-pressure rise may justify a planned task. A sample result or contamination event that may represent a danger to human health requires a different level of urgency and regulatory involvement.

If the local authority considers the supply a potential danger to health, Regulation 15 requires consumer information and advice. DWI's Regulation 18 guidance explains that a notice can prohibit or restrict use and must specify action needed to safeguard human health, restore acceptable water and maintain it afterward.

DWI gives examples of restrictions, including boiling for appropriate microbiological risks and not using water for drinking/food preparation for certain serious chemical risks. These examples are not a decision tree for operators. The correct restriction depends on the hazard and professional/public-health assessment. Boiling can be inappropriate for some chemical contamination and is only a short-term control even where it is suitable.

When the problem is insufficiency

A private supply can fail operationally because there is not enough water, even where no parameter failure has been identified. DWI's current insufficiency guidance treats this mainly through the Water Industry Act 1991. Section 80 gives local authorities powers where a supply is failing, has failed or is likely to fail to provide a wholesome and sufficient supply for domestic purposes.

For operators and relevant persons, DWI recommends clear documented contingency procedures for temporary interruption, especially for Regulation 9 commercial/public supplies. A corrective-action record should capture the date the shortage began, affected users, source or pump/storage issue, temporary supply arrangements, communications, consumption/demand information, repairs and the longer-term resilience measure. Keep detailed emergency arrangements in the separate emergency-plan record rather than duplicating them here.

Keep corrective actions distinct from other records

Corrective actions sit between several other records, but they should not replace them:

• Failed-test guidance explains what a result can trigger and how to preserve the laboratory evidence.
• Notices guidance focuses on formal notice documents and deadlines.
• Change management records material alterations to source, treatment, distribution or use, whether or not they began as a failure.
• Maintenance records cover planned/routine servicing and inspections.
• Risk-assessment guidance explains the local authority's Regulation 6 role.
• Treatment guidance covers treatment selection, limitations and operation.

This guide's search intent is narrower: what to record after a problem, failure or identified risk, and how that record relates to the regulator's investigation and follow-up.

England and the other UK nations

This guide is written for England and uses the Regulation numbers in the Private Water Supplies (England) Regulations 2016 as amended. Do not reuse those numbers as if they apply UK-wide. Wales uses the Private Water Supplies (Wales) Regulations 2017, where equivalent duties have different numbering; Scotland and Northern Ireland have their own private-water-supply regimes. Use the applicable regulator/local authority guidance for the nation where the supply is located.

Frequently asked questions

Related guidance and tools