contaminants in freshwater and wastewater interlaboratory testing

Freshwater and wastewater

Proficiency tests

The proficiency tests in the freshwater and wastewater programme are a continuation of the proficiency tests previously organised by Rijkswaterstaat (RWS-CIV) in the Netherlands. Rijkswaterstaat is the implementing agency of the Dutch Ministry of Infrastructure and Water Management and has organised proficiency tests in freshwater and wastewater until 2022 to support Dutch and Belgian laboratories involved in national monitoring. WEPAL-QUASIMEME was already the supplier of the test materials used in these proficiency tests. From 2023, WEPAL-QUASIMEME offers the full organisation of these proficiency tests and five new proficiency tests for freshwater and wastewater were added.

Participation is open to all laboratories worldwide, however, some determinands are only suitable for local laboratories as analysis needs to be performed on fresh samples. Preservation of samples is not applicable for all types of determinands.

Determinand Group Sample Type Exercise
Metals (e.g. Cd, Cu and Zn) Wastewater FW1
Metals (e.g. Cd, Cu and Zn) Freshwater FW2
Dried residue Freshwater and wastewater FW3
General parameters Freshwater FW4
Charge and general parameters Wastewater FW5

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General information

  • Fresh- and wastewater samples are mainly prepared from local Dutch surface water and wastewater from Dutch wastewater treatment plants.
  • Water samples are filtered using a 1 mm filter.
  • The preserved water samples are stable for the period of the test when stored properly.
  • Some of the PT samples from FW3, FW4 and FW5 are not stable and will be provided with a required date of analysis.
  • All fresh- and wastewater samples are prepared in bulk and tested for its homogeneity where relevant.
  • Use your normal validated methods and procedures to analyse the test materials.
  • New determinands can be added to these programs on request.
  • Reports contain all data reported under strict confidentiality, including Z-score plots and method information of methods used.


Samples of previous proficiency tests are sold as reference materials. Available materials can be selected and ordered in our webshop. Participants are entitled to a discount.