Significant changes to the requirements for the testing of drinking water supplies have been announced by the Drinking Water Inspectorate (DWI). The changes, which affect both public and private supplies relate to the arrangements for demonstrating that the laboratory analysis of drinking water samples and associated reporting of analytical results meet regulatory requirements.
In order to comply with the Water Supply (Water Quality) Regulations and the Private Water Supplies Regulations, samples must only be analysed by a laboratory that has in place a system of analytical control that is subject to checking by an approved body. As the UK’s National Accreditation Body, the United Kingdom Accreditation Service (UKAS) is the approved body for England and Wales.
Consequently, the DWI has mandated that all laboratories carrying out analysis of drinking water must obtain and maintain UKAS accreditation equivalent to ISO/IEC 17025:2005 The General Requirements for the Competence of Testing and Calibration Laboratories. Accordingly, each water company and local authority must ensure that the laboratories to which regulatory samples are submitted are appropriately accredited.
Laboratories in England and Wales can seek a further specific scope of accreditation for a sector scheme known as the Drinking Water Testing Specification (DWTS). DWTS is already compulsory for laboratories undertaking testing of drinking water in Scotland and Northern Ireland.
Paul Greenwood, Divisional Director (Laboratories) at UKAS said “Opting for accreditation under the DWTS scheme significantly reduces the burden of DWI audits, as the need for DWI to routinely audit or inspect the laboratory is removed. Conversely, if a laboratory chooses not to adopt DWTS they will be subject to risk based vertical audits, including audits of samplers, by DWI. From January 2013 onwards the costs of DWI audits or inspections of laboratories used by water companies will be recovered by the DWI, so there are also financial benefits to being accredited under the DWTS scheme.”
UKAS is currently revising its LAB 37 publication Accreditation Requirements for Sampling and Testing in Accordance with the Drinking Water Testing Specification (DWTS) document in consultation with the DWI to reflect the new requirements.
 Guidance on The Implementation Of The Water Supply (Water Quality) Regulations: Appendix 1: Regulation 16 – Analysis Of Samples
 Legislative Background to the Private Water Supplies Regulations 2009 Section 9: Section 18.104.22.168 to 22.214.171.124 on Schedule 3 of the Regulations