Legal Instruments

Water companies, if required by or with the agreement of, the Inspectorate, can be subject to programmes of remedial actions to improve drinking water quality with legally binding milestones and reporting stages. These plans and projects are discussed and agreed between the water company and the Inspectorate following breaches, or possible breaches, of regulations. All decisions regarding enforcement, are made in line with the Inspectorate’s Enforcement Policy.

A legal instrument can arise from multiple routes and can vary in type. A legal instrument encapsulates a package of measures to address a risk to water quality, and legally binds a water company to complete these measures. The risks also vary, for example from old pipes causing discoloured water, to a deteriorating water treatment process. As a result, the measures also vary, from replacing old water pipes to rebuilding whole water treatment works. Legal instruments can span a few months to several years depending on the scope of the measures. Legal instruments, where applicable, will include ongoing measures to ensure any risks are mitigated until the permanent mitigating measures can be implemented.

  1. Price review process

As part of OFWAT’s (the water industry’s financial regulator) process for setting price limits, companies include proposals for improvements and capital maintenance in business plans every five years. Where a water quality risk or future risk is identified in these proposals, the Inspectorate will support a company’s proposal and convert the proposal into a legal instrument.

2. Breaching drinking water standards for parameters

Water companies are required to take a specified number of water samples across their assets and network. Should any of these samples fail to meet the prescribed drinking water standard, an investigation must take place. If the investigation identifies the failure is likely to recur, enforcement action (such as the issuing of a legal instrument) will be initiated to prevent this.

3. Event and audit assessments

Companies are required to notify the Inspectorate of water quality events. A programme of risk-based audits is completed by the Inspectorate throughout the year. Legal instruments can be generated from both of these areas where unmitigated risks to water quality or human health are identified.

4. Risk assessment

Water companies are required to carry out risk assessments of all their treatment works and connected supply systems, from catchments to consumers’ taps. Companies are required to submit these risk assessments to the Inspectorate. Where the assessments highlight a risk of supplying water that could constitute a potential danger to human health or could be unwholesome, a legal instrument can be served to require the company to mitigate the risk.


Notices are the most commonly used and are linked directly to risk assessments carried out by the water companies.


Undertakings allow a route for a company to voluntarily come forward to the Inspectorate, to commit to a legally binding programme of work to where they have identified a risk to water quality. They are also a ‘stay’ on the use of an enforcement order.

Enforcement Orders

Enforcement Orders are rarely used but are considered for use where the failures are of a serious nature, or if a company fails to deliver on agreed actions in either an undertaking or notice.

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