Enforcement Policy – Drinking Water Quality Regulation


The Drinking Water Inspectorate (the Inspectorate) is the quality regulator for public water supplies in England and Wales. Our work provides assurances that safe and acceptable drinking water is supplied to the public. We have been appointed to act in these matters on behalf of the Secretary of State for Environment, Food and Rural Affairs and the Welsh Ministers under the Water Industry Act 1991 (“the Act”), including certain duties which are vested directly into the Chief Inspector of the Inspectorate.

Primarily, our work involves the regulation of water companies that provide public water for drinking, cooking, food production and domestic purposes. Our regulation of these companies follows a self-assurance model, whereby companies monitor their own performance (as dictated by regulatory requirements, for example the regulatory duty to complete risk assessments and take water samples). Periodically we audit the performance of those we regulate, based on risk.

This Enforcement Policy document sets out the general principles we follow in relation to our powers of enforcement. These principles, so far as they are relevant, will also apply to our role of overseeing and supporting regulation of private water supplies by local authorities in England and Wales.

The Enforcement Policy takes account of our strategic objectives[1] which are available on our website.

This policy will be kept under review and updated to reflect changes in law, policy, better regulation and learning from its implementation.

In conjunction with this policy, we also publish information, guidance, protocols and tools on our website[2] to help those we regulate with any submission to us and to understand compliance.

Better Regulation

We consider that the best way to ensure that water companies comply with their legal and regulatory requirements is through guidance and advice, ensuring that those carrying out regulated activities understand the nature and extent of their responsibilities and comply voluntarily.

However, there are times when compliance needs to be secured through enforcement action. Formal enforcement is about securing compliance with regulatory requirements. To this end there is a spectrum of civil and criminal sanctions available to us, these include:

  • statutory notices or orders requiring or prohibiting companies to take certain steps (which in some instances result in an offence if not complied with);
  • statutory undertakings; and
  • criminal prosecution before the courts.

This policy sets out how we determine the most appropriate choice of sanction in any case. In determining this, we will ensure that we have regard to relevant regulatory duties and guidance, which include:

  • The Legislative and Regulatory Reform Act 2006[3] (as amended) and the Legislative and Regulatory Reform (Regulatory Functions) Order 2007 (as amended)[4]. These pieces of legislation require that regulatory functions (including enforcement) are carried out in a way which complies with the principles of transparency, accountability, proportionality and consistency, and will only be used in cases where action is needed.
  • The Regulators’ Code[5] sets out that regulators should:
    • carry out their activities in a way that supports those they regulate to comply and grow;
    • provide simple and straightforward ways to engage with those they regulate and hear their views;
    • adopt a risk-based approach to regulatory activity;
    • share information about compliance and risk;
    • ensure clear information, guidance and advice is available to help those they regulate to meet their regulatory duties; and
    • ensure their approach to regulatory activities are transparent.
  • The government’s guidance under section 110(6) of the Deregulation Act 2015[6], which requires that regulators consider the importance for the promotion of economic growth of exercising the regulatory function in a way which ensures that regulatory action is taken only when it is needed, and any action taken is proportionate. This duty does not apply to decisions as to whether to institute or conduct criminal or civil proceedings.

The effective use of enforcement powers is important to secure compliance with the law and, where necessary, to ensure that those who have not complied are held to account. Enforcing authorities need to maintain a balance between enforcement and advisory activities when allocating resources.

In situations where a criminal course of conduct could be investigated and prosecuted by more than one investigative or prosecuting authority, we will coordinate with these authorities from the earliest possible stage. Where appropriate, we may combine our enforcement action with other authorities so that only one investigation and prosecution will take place, with one authority acting as the lead coordinator. Where this is not possible, we will coordinate with the other authorities to ensure that the public can have confidence in the outcome of each case and the law is enforced in a fair and effective way.

Whenever possible we will work with other regulators and authorities to amplify the positive impact of enforcement action. This includes establishing and keeping up-to-date relevant Memoranda of Understanding with other regulators and authorities as appropriate.

Our complaints procedure[7], which is available on our website, can be followed for any complaints relating to our enforcement activities.

Principles of enforcement

Having regard for the legislation and guidance set out above, we adopt the enforcement principles set out in the following sections.


We must be able to justify decisions made within the context of the regulatory framework within which we operate. The Act describes the Inspectorate’s duties, which include the duty to enforce in specified circumstances. We will explain the reasoning behind any enforcement action we have taken or propose to take to the relevant parties concerned.

Details of enforcement action we have undertaken is published (in an accessible format) on our website. In the case of enforcement orders that we propose to make, this will include the publication of the notice to initiate enforcement (section 20 notice) as well as the draft order, for the duration of the period within which representations or objections may be made.

The Rehabilitation of Offenders Act 1974[8] requires us to remove published information on convictions and cautions of persons after a certain duration. The duration will depend on the nature of the offence or penalty. This does not apply to publication of cautions or convictions of companies.

We will meet the requirements of the data protection legislation by not publishing information on an individual (as opposed to a company) unless required to by law. Public register and other requirements may override this exclusion.


Proportionality in securing compliance with drinking water law will generally involve taking account of the degree of the risk of adverse consequences resulting from non-compliance. This will primarily include consideration of the level of risk (actual or potential) to human health or loss of public confidence in drinking water quality. The type and nature of enforcement will also take account of the person’s or company’s history of compliance with its legal and regulatory obligations and past performance. We may be required to adopt precautionary measures (such as enforcement) to protect human health even when scientific evidence may not be certain, but the risks are high. In such cases, our decisions will be guided by the best available evidence as to the likelihood of the realisation of those risks and the severity of the risk posed to human health.


To remain consistent, we shall apply a similar approach in similar cases, to achieve similar outcomes. There remains a degree of discretion, to account for wider factors such as the attitude and level of competence of the person or company (in reference to any person or company specified in the legislation) in bringing about the outcome sought.

Our enforcement team operate nationally and maintain a view of water quality across England and Wales. The final decision on whether enforcement action should be pursued or not, is made by the Principal Inspector for Enforcement (or nominated representative), the Deputy Chief Inspectors or the Chief Inspector. This ensures consistency in our approach.


To be transparent with those we regulate, we shall:

  • Help them understand what is required to comply with the law.
  • Set out what they may expect from us in return.
  • Clearly outline why we have taken or intend to take enforcement action.
  • Make clear what breach or offence we consider is being or has been committed.
  • Provide details of any rights of appeal or opportunity to make representations or objections.

We promote a culture of openness and honesty both within our own organisation and in our interactions with those we regulate. We expect those we regulate to mirror this culture of openness and honesty in their interactions with us.


Targeting enforcement action means prioritising and directing regulatory effort effectively where it can have the most beneficial impact. This means concentrating on the activities that create or could create the most significant risk, either because the nature of the activity is inherently high-risk or because of a lack of appropriate controls or appropriate attitude of the person or company. Additionally, this involves identifying and focusing on evidence of systemic risk or behaviour not conducive to effective risk management, including the timeliness of persons’ or companies’ response to risk and in their engagement with us.

Enforcement Options

Investigation of the circumstances or matters discovered on inspection, following a complaint, or identified by assessment of data, are vital. However, such an investigation will not necessarily be a criminal investigation. We will seek a resolution of matters by taking the most appropriate enforcement option, or combination of options, on a case-by-case basis.

There are several enforcement options open to us; a summary of these has been provided in Table 1. The tiered enforcement options and sanctions are explained in further detail in section 5 and onwards.

Regulatory Action

Description of regulatory action


Advice that can be used to secure improvements or better practices. Used where there has not been or is not likely to be a regulatory breach (or potential breach) of regulation.


Issued to secure required improvements to prevent a breach, prevent a potential breach or to prevent a reoccurrence of a breach of regulation.


There are several types of notices that we can serve. Generally, notices encompass a set of requirements that the person or company must do to mitigate a risk by a specified date, but they can also include specific instructions, such as a requirement for specific samples to be taken. Failure to comply with the required steps, can result in prosecution or further enforcement.


An undertaking is a commitment, given by the regulated person to the Inspectorate, to take certain steps in order to secure or facilitate compliance with their duties or regulatory requirements. Undertakings are treated as statutory requirements under the Act. Undertakings are made subject to the requirements of the Drinking Water (Undertakings) (England and Wales) Regulations 2000[9]. We will consider whether an undertaking should be accepted on a case-by-case basis.

Provisional enforcement order (PEO)

An order which stipulates the steps the person or company must do or must not do by a specified date, to achieve compliance with the requirements enforceable under section 18 of the Act. A provisional enforcement order can be used where there is an imminent risk that requires enforcement before a final enforcement order may be made (and which can subsequently be confirmed). We may also use orders as an escalation route for failures to comply with a notice or undertaking.

Final enforcement order (FEO)

An order which stipulates steps the person or company must do or must not do by a specified date, to achieve compliance with the requirements enforceable under section 18 of the Act. We may also use orders as an escalation route for failures to comply with a notice or undertaking.

Criminal investigations

Where a person or company is suspected of committing an offence, a criminal investigation may be initiated to assess whether an offence may have been committed. Criminal investigations can lead to warnings, cautions or prosecutions.


Where there is evidence that an offence has been committed and we do not consider a caution or prosecution to be appropriate, we may issue a letter to the offender, setting out the offence and a warning that any further repeat offences could result in further sanctions.


Where there is evidence that an offence has been committed and we do not consider prosecution to be appropriate and the offender has admitted committing the offence and consents to be cautioned, we may issue a caution to the offender (which may include conditions to be complied with by the offender). Failure to comply with the conditions of a caution can result in criminal proceedings against the offender.


We can prosecute a person or business we believe has committed a crime against the legislation we enforce. This would mean laying formal charges against a person or company in a legal court.

Table 1: Explanation of the regulatory action used by the Inspectorate

We follow a graduated approach to enforcement, where our response will reflect the level of risk. For instance, we may decide that circumstances do not warrant the serving of a legal instrument (see section 5.3) or criminal sanctions. In such cases, we may write (for example, as an audit inspection letter or report, a compliance assessment letter or an event assessment letter) to the person or company with suggestions to improve performance, or recommendations of actions they should take in order to achieve compliance or remain compliant. However, failure to follow recommendations where risk has or is likely to increase may result in the escalation of our enforcement action towards civil or criminal sanctions. In other instances where risk is assessed as being or has been high, this could warrant the immediate serving of a legal instrument or a criminal sanction. In any event, we will take a proportionate approach.


We may make a suggestion to a person or company where we have observed an opportunity for improvement, noted a deficiency or observed a deviation from good practice. Suggestions are only used where a regulatory breach, or potential breach, will not or has not occurred. Suggestions are informal, and although we encourage suggestions to be considered, companies are not required to submit formal responses to any suggestions we may make. Suggestions do not become part of the enforcement record of that person or company.


Where there is or has been a breach of regulation (or a likely breach) and we are unable to conclude whether the breach is likely to reoccur, we may make a written recommendation requiring the person or company to address the deficiency. In turn, a written response to a recommendation is required from the person or company. Recommendations, and information as to whether the company has complied with them, are kept on a person or company’s regulatory performance record.

We measure water company performance based on the number of recommendations they have received from us, the type and severity of the recommendation and the quality of the company’s response to our recommendation. This is calculated as the Recommendation Risk Index. The Recommendation Risk Index is reported publicly in the Chief Inspector’s reports, which are available on our website.

The Inspectorate is granted enforcement powers in respect of breaches of drinking water law that include (but are not limited to) the following types of legal instruments:

  • notices under the Water Supply (Water Quality) Regulations (2016 in England, 2018 in Wales);
  • undertakings offered by specific persons or companies under section 19 of the Act; and
  • provisional or final enforcement orders under section 18 of the Act.

We will serve legal instruments according to our assessment of the level of risk posed in the circumstances of the case. For example, where we do not consider there to be an immediate risk to public health, we will write to the person or company, explaining that we are minded to enforce with a legal instrument. In doing so, we shall clearly outline the legal instrument we propose to serve and the reasoning behind this. We will also stipulate the period during which representations or objections regarding the proposed enforcement may be made to us and how.

After the period has ended, we will consider any representations or objections made (which have not been withdrawn) to determine whether we should proceed with enforcement. Where any representations or objections made show that the risk has been satisfactorily addressed, we may subsequently determine that the need for enforcement action is negated; our reasoning for doing so will be explained in writing. Where we feel the risk remains, we will serve the legal instrument and explain our reasoning for doing so in writing, when the legal instrument is served.

Where an immediate risk to human health is apparent, a legal instrument may be served without a period for representations or objections. We shall outline our reasoning for doing so, in writing, when the legal instrument is served. This is not applicable to all legal instruments as some by law require a period within which representation or objections may be made.

Failure to comply with legal instruments may lead to further enforcement action being taken by us, which may include:

  • An enforcement order being made for the failure to comply with the requirements of a notice served under the Water Supply (Water Quality) Regulations.
  • The commencement of civil proceedings, in order to obtain an injunction or other appropriate relief.

Our commitment to consider representations or objections does not displace the statutory right of the company or person aggrieved by an enforcement order to make an application to the High Court under the Act.

Criminal investigations and enforcement

A criminal investigation is carried out to gather evidence to assess whether an offence may have been committed. That evidence may ultimately be used in a criminal trial. Persons or companies that are guilty of an offence, can be liable upon conviction to a fine or other criminal sanctions.

In criminal investigations, special provisions apply for the protection of suspects. Most notably, suspects are entitled to be cautioned in accordance with Code C[10] of the Codes of Practice made under the Police and Criminal Evidence Act 1984[11].

Criminal investigations will always be led by our inspectors, who are appointed under the Act to conduct such investigations. We may appoint other specialist persons, on a temporary basis, to assist our inspectors in the conduct of such an investigation. It is an offence for a person or company to obstruct an appointed inspector in the course of such duties.


The decision on whether to commence a prosecution is taken by the Chief Inspector, independently of the lead inspector. In deciding whether to commence a prosecution, the Chief Inspector will have regard to the Code for Crown Prosecutors[12], particularly in relation to the factors set out below.

Sufficiency of evidence

The Chief Inspector will only commence a prosecution when satisfied that there is a realistic prospect of conviction on the available evidence.

If the sufficiency of evidence test is not met, then the Chief Inspector will consider whether another form of response is more appropriate.

Public interest factors

In addition to relevant matters set out in the Code for Crown Prosecutors relating to the personal circumstances of the offender and the circumstances of the offence, the Chief Inspector will consider other factors in deciding whether to prosecute. These factors include:

  • The impact or potential impact of the offence on consumers, having regard to our strategic objectives.
  • The implications of the offence for the credibility and enforcement of the regulatory regime.
  • The perceived benefit accruing to the offender from not being duly diligent.
  • Whether the offence was committed deliberately as opposed to whether it was committed accidentally or was a genuine mistake.
  • Whether inspectors were obstructed in the course of their duties.
  • Whether the alleged offender has been issued with previous written advice or guidance from us which, if followed, would have reduced the likelihood of an offence being committed.
  • The previous enforcement record of the alleged offender.
  • The attitude of the alleged offender, including behaviour towards inspectors, and whether robust and permanent corrective measures to remedy the offence or prevent any reoccurrence are or have been put in place.
  • The risk of other similar offences being committed by the alleged offender.
  • The general deterrence of others who may be tempted to offend.
  • Whether false or misleading evidence has been provided.
  • Whether the offence is motivated by financial gain.
  • The alleged offender’s personal circumstances, including serious ill health, age and maturity at the time of the offence and the ability to pay if the sanction includes a fine imposed by a court or requirement to carry out costly remediation.
  • Whether the offence arose from unusual circumstances where the situation could not have been foreseen or reasonable precautions have previously avoided the situation; and reasonable steps were taken to mitigate the matter and the appropriate authorities promptly notified.

Body Corporate

Where an offence is the result of a company’s activities, we will usually enforce against the company.

Where an offence is committed by a body corporate with the consent or connivance of, or attributable to any neglect of, any director, manager, secretary, other similar officer or any person acting in this capacity, that person could also be guilty of an offence. We may enforce against that person.

We may take action against a company, person or both.

Warning letters

Where there is evidence that an offence has been committed and a caution is not appropriate, the Chief Inspector may decide to issue a formal warning in writing, informing the person or company that has committed an offence. The issue of a warning letter will become part of the enforcement record of that person or company and will be published on our website.

Any continued or further breach following a warning letter, may be considered in determining future enforcement action.


We can only consider the use of a formal caution where we believe we could commence a prosecution and the offender:

  • admits to us that they committed the offence; and
  • consents to be cautioned.

Formal cautions are given in writing to the offender. If the offender does not accept the caution, we will typically prosecute for the original offence.

Following the issuing of a caution, should new evidence come to light that suggests the offence committed is more serious, a prosecution may still be brought against the offender.

The issue of a caution will become part of the enforcement record of the offender and will be published on our website. Any continued or further breach following a caution, will be considered in determining future enforcement action.

Private water supplies

Local authorities are responsible for the enforcement of private water supplies. Where a local authority serves a section 80 (of the Act) private supply notice, the person who it is served upon may make written representations or objections to that local authority. Where representations or objections are made to the local authority, that notice will not take effect unless:

  • the notice is submitted to the Chief Inspector (acting on behalf of the Secretary of State); or
  • the representation or objection is withdrawn.

If the notice is submitted to the Chief Inspector, they will consider whether the notice should be confirmed and whether, if it is confirmed, it should be confirmed with or without modifications. Within the considerations, the Chief Inspector must review (amongst other things) whether a notice has been served on the correct grounds and on the right people, whether the remedial steps are appropriate, and whether the procedural safeguards have been followed.

After concluding these considerations, the Chief Inspector will write to the local authority, the persons and companies involved, explaining whether they have decided to confirm the notice, with or without modification.


This policy was developed in consultation with those we regulate, the Environment Agency, Natural Resources Wales, CC Water, Ofwat, Defra and Welsh Government. It replaces the Inspectorate’s previous Enforcement Policy dated February 2016.

Any questions regarding this policy should be addressed to DWI.Enforcement@defra.gov.uk

Footnote References

  1. https://www.dwi.gov.uk/what-we-do/our-strategic-objectives/

  2. https://www.dwi.gov.uk

  3. http://www.legislation.gov.uk/ukpga/2006/51/pdfs/ukpga_20060051_en.pdf

  4. http://www.legislation.gov.uk/ukdsi/2007/9780110788708/pdfs/ukdsi_9780110788708_en.pdf

  5. https://www.gov.uk/government/publications/regulators-code

  6. Statutory Guidance under section 110(6) of the Deregulation Act 2015, Growth Duty: Statutory Guidance (publishing.service.gov.uk). This guidance concerns the performance of the growth duty in section 108 of the Act and sets out ways in which regulators can exercise their regulatory functions in accordance with the growth duty.

  7. https://dwi.gov.uk/drinking-water-inspectorate-complaints-procedure/
  8. Rehabilitation of Offenders Act 1974 (legislation.gov.uk)
  9. The Drinking Water (Undertakings) (England and Wales) Regulations 2000 (legislation.gov.uk)
  10. Pace Code C (Revised) (publishing.service.gov.uk)
  11. http://www.legislation.gov.uk/ukpga/1984/60/pdfs/ukpga_19840060_en.pdf
  12. https://www.cps.gov.uk/publication/code-crown-prosecutors
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