Sampling accreditation scheme


The Inspectorate has developed an accredited training scheme, alongside sampling Procedures and manuals to assist local authorities to comply with the ISO/IEC 17024 requirement within the Regulations (The Private Water Supplies (England) (Amendment) Regulations 2018 and the Private Water Supplies (Wales) Regulations 2017 require local authorities to demonstrate that the sampling, transportation, and storage of private water supplies complies with the ISO/IEC 17024 standard).

Any person collecting, transporting and storing samples of private water supplies, must comply with the procedures contained within this manual. In practice, this means becoming a certified sampler.

CATG provide accredited training and award certification (telephone number 01524 400632 and website).

Local authorities are advised to complete the required certification as soon as possible and as Government guidance allows. Certification became a requirement from 11th July 2020 in England and 20th November 2019 in Wales. Consequently local authorities should contact CATG to arrange for training. If the sampling procedures of a local authority, or its chosen contracted sampling service provider are already accredited to the ISO/IEC 17025 standard, then it does not require its samplers to be certified in accordance with the ISO/IEC 17024 sampling scheme.

Scheme document

Further information on the certification scheme can be found in the scheme document.

Sampling Manual

The Sampling Manual should be used by local authorities as the basis for developing their own local version for their sampling officers. It is a controlled document. However, it may be adapted to produce a local version, provided the following criteria are observed:

  • The order of sampling cannot be changed.
  • Microbiological methods cannot be changed.
  • Chemistry methods can be changed where they can be justified by the accredited laboratory service provider.
  • Maintain the methodology as per the scheme procedure wherever possible
  • Transportation and sample handling procedures can be tailored to the local situation, but must meet the overall regulatory requirements.
  • Methods shown in the appendices are not part of the accreditation, and are provided as examples of good practise for investigational sampling and to provide examples of record templates.
  • Other relevant local provisions such as local health and safety references or policy can be included.

Further information on sampling can be found within the Scheme Sampling Manual itself. 

ISO 17024 Scheme Sampling Manual

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Further guidance in developing local manual can be found in the Guidance for Local Authorities on Developing Private Water Supplies Sampling Manuals.

Local authorities are advised to familiarise themselves with these procedures.

DWI will be monitoring progress with training and accreditation, and will report on the position in our annual report.

Sampling and monitoring for Regulation 8 supplies (private distribution systems)

The monitoring of each Regulation 8 supply must be based on the outcome of the regulatory risk assessment carried out for that supply. The relevant parameters and frequency of sampling should reflect the risk rating and the nature of the hazards identified in the risk assessment:

  • coliforms and E.coli (ingress into the network or poor hygienic conditions, especially tanks)
  • colony counts (upward trend may indicate deterioration of water quality)
  • conductivity, hydrogen ion and turbidity
  • iron and zinc (from corrosion of galvanised steel or cast iron pipes), manganese, aluminium
  • taste and odour (ingress and permeation of plastic pipes)
  • trihalomethanes and bromate (disinfection by-products) (especially if there is chlorination within the private distribution network)
  • lead, nickel and copper (from the pipe work or tap fittings in the private distribution network or within the premises.
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