The mission of the PT-WFD network is to provide harmonised proficiency testing (PT) schemes that

• meet the specific requirements of the European water framework directive (WFD)
• are performed and evaluated in a harmonised and comparable way

This includes:

• Harmonized performance evaluation of European labs involved in WFD monitoring analysis
• Organisation of Pan-European PTs for analytes that are analysed only by few labs
• Economically sound organisation of PT schemes due to synergy effects with other PT providers
• Regular scientific input from external advisors
• Combined forces on new developments and gaps in the spectrum of needed WFD PT schemes

with the following features

• Harmonisation and ensuring a high quality of PTs through
  • Operation in accordance with ISO/IEC 17043
  • Evaluation of data according to ISO 13528
• High quality and fitness of PT samples for WFD
  • Matrix, typology and concentration level of analytes adapted to WFD requirements
• Common criteria for
  • Definition of assigned values
  • Definition of the standard deviation for performance assessment (SDPA)
  • Assessment of laboratory performance on the basis of z-scores