Guidance and codes of practice

Guidance on implementing the Water Supply (Water Quality) Regulations

Long term planning guidance – Resilience of Water Supplies in Water Resource Planning (PDF 148KB)

Private Water Supplies Guidance

DWI Reports with recommendations and lessons-learnt applicable to all water suppliers

Bouchier report Cryptosporidium in Water Supplies (PDF 1.57MB 184 pages) Third report of the Group of Experts November 1998

Badenoch Summary report of the Group of Experts on Cryptosporidium in Water Supplies (PDF 2.06MB 24 pages – scanned copy only)

Other Technical Guidance and codes of Practice

The Drinking Water Inspectorate produce guidance notes for regulations and procedures and codes of practice that the water industry must adhere to. A list of current documents can be found below.

The Standing Committee of Analysts (SCA) comprises a series of working groups who provide guidance on methods of sampling and analysis for determining the quality of environmental matrices. Guidance is published as Blue Books within the series Methods for the Examination of Waters and Associated materials. The guidance can be found on the SCA website 




Guidance Note: Long term planning for the quality of drinking water (PDF 64MB)


Guidance on the Notification of Events (Version 1.2) (PDF 529KB)


Guidance on Alternative Supply Operations (PDF 206KB) Issue date 21 March 2022 as mentioned Information Letter 01/2022


Drinking Water Safety – Guidance to Health and Water Professionals



Wales (Welsh)


Code of Practice on Technical Aspects of Fluoridation of Water Supplies 2021 (PDF 561KB) Issue date 6 September 2021 as mentioned in Information Letter 04/21


Guidance on the Water Supply (Water Quality) Regulations 2016 specific to PFOS (perfluorooctane sulphonate) and PFOA (perfluorooctanoic acid) concentrations in drinking water. (PDF  176KB)

Guidance on the Water Supply (Water Quality) Regulations 2016 specific to PFOS (perfluorooctane sulphonate) and PFOA (perfluorooctanoic acid) concentrations in drinking water.(html)


Guidance on the regulatory responsibilities of new (inset) appointees in relation to public water supplies (PDF 268KB)


Guidance on Consumer Complaints (Version 1.1) (PDF 89KB)


Guidance for reporting on Undertakings for metaldehyde and/or other pesticides in March 2017 (PDF 314KB)


Guidance on the use of ultraviolet (UV) irradiation for the disinfection of public water supplies (PDF 266KB)


WHO Technical Brief – Boil Water (PDF 726KB)


Authorisation of different standards (PDF 135KB)


Joint Drinking Water Inspectorate/Environment Agency Guidance: The Contribution of the Water Supply (Water Quality) Regulations to the implementation of the Water Framework Directive in England & Wales (PDF 480KB)


World Health Organisation – Guidelines for drinking water quality – 4th Edition (PDF 66KB)


Rain water harvesting systems – Event in Upton Eco-Housing Development, Northamptonshire, June 2010 (PDF 213KB)


Guidance on sample and sample extract stability trials (PDF 169KB) and
Guidance on sample preservation ad preparation for metal analysis of drinking water (PDF 102KB) – Issue date 22 August 2005
As mentioned in Information letter 12/2005


Guidance on calibration and analytical quality control for residual chlorine measurements (PDF 169KB) – Issue date 24 January 2005


A Brief Guide to Drinking Water Safety Plans (PDF 256KB)


Common Carriage: Guidance on the drinking water quality aspects (PDF 214KB) – Issue date 24 November 2004


Guidance on the interpretation of aspects of analytical quality control (AQC) (PDF 175KB)

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