Improvement programmes

Water companies, if required by the Inspectorate or with the agreement of the Inspectorate, can put in place programmes of remedial action to improve drinking water quality whenever these are necessary.

Programmes of work arise in four ways:

  • as a result of the process for setting price limits for a five year period (known as the price review process);
  • as a result of enforcement for contraventions of the drinking water standards for parameters in the regulations; and
  • as a result of enforcement for issues arising out of an assessment by the Inspectorate of a drinking water quality incident or technical audit;
  • following the identification of a risk to health through a risk assessment of a water supply system.

More detail is provided in the Guide to Improvement Programmes.

Audit Strategies are a vital part of any improvement programme. A copy of the audit strategy guidance we have been rolling out to companies is provided here for reference.

DWI Audit Strategy Guidance

Request an accessible format.
If you use assistive technology (such as a screen reader) and need a version of this document in a more accessible format, please email Please tell us what format you need. It will help us if you say what assistive technology you use.


The Secretary of State or Welsh Ministers may notify a water undertaker that, for specific water supply zones, a radioactive parameter need not be monitored, providing those parameters (Indicative Dose, Tritium, and Radon) are below the respective parametric values.

Radioactivity notices are issued to companies where sufficient risk assessment and sample analysis demonstrates a low risk. This is allowed under regulation 6(12) of the Water Supply (Water Quality) Regulations 2016 (as amended) and 6(14) of the Water Supply (Water Quality) Regulations (Wales) 2018.

Monitoring Variations

Companies who meet the requirements of regulations 9(8) and 9(11) of either the English or Welsh Regulations, and who have had their risk assessment methodology approved by the inspection body (Lloyds Register) can apply to the Secretary of State or Welsh Ministers for a monitoring variation under regulation 9(6)(b).  A monitoring variation can either be a cessation of all compliance monitoring or a reduction of compliance monitoring for specific parameters.

Under regulation 9(6)(a) of either the English and Welsh Regulations, the Secretary of State or the Welsh Ministers may also initiate a monitoring variation by their own motion, to cause a company to vary the amount of compliance monitoring for specific parameters.

Improvement Programmes for NIS and for SEMD

Notices may be served under the Network and Information Systems (NIS) Regulations. Enforcement orders can be made or undertakings accepted under the Water Industry Act 1991, to secure compliance with the Security and Emergency Measures (Water and Sewerage Undertakers and Water Supply Licensees) Direction. In accordance with our enforcement polices, these legal instruments are not published in the public domain in order to protect security.

Improvement Programmes, Radioactivity Notices and Monitoring Variations by Company:

Affinity Water Limited

Albion Eco Limited

Albion Water Limited

Anglian Water Services Limited

Dwr Cymru Welsh Water

Hafren Dyfrdwy

Icosa Water Services Limited

Independent Water Networks Limited

Leep Networks (Water) Limited

Northumbrian Water Limited

Portsmouth Water Limited

Severn Trent Water Limited

South East Water Limited

South Staffordshire Water Plc (including Cambridge Water)

South West Water Limited (including Isles of Scilly, Bournemouth Water and Bristol Water)

Southern Water Services Limited

Sutton and East Surrey Water Plc (SES)

Thames Water Utilities Limited

United Utilities Water Limited

Veolia Water Projects Limited

Wessex Water Services Limited

Yorkshire Water Services Limited

Back to top