The origin of the EQAT inter-laboratory test

The EQAT scheme has its origin in the quality management activities of the biology workgroup of the Arbeitsgemeinschaft Trinkwassertalsperren (ATT e.V.) in the 1990s. Since 2002, the proficiency test phytoplankton has been carried out on an international level by the LTV.

Preparations for the 2025/2026 EQAT scheme are in progress

Due to problems with the earlier schedule, the upcoming proficiency test has been postponed. Preparations are already running at full speed!

Registration is planned from mid-May to mid-August 2025. The analysis phase is planned from the beginning of November 2025 to the end of February 2026. We hope that it will be another interesting interlaboratory test.

Proficiency test phytoplankton 2025 / 2026

Registration starts May 2025

Why to take part in a proficiency tests and why participating in our EQAT scheme?

Inter-laboratory comparisons are an essential part of external quality assurance. Laboratories can test and improve their analytical performance. The EU Water Framework Directive sets high standards for the quality of phytoplankton analysis and requires regular participation in proficiency testing. EQAT Phytoplankton organises such ring trials every 2 years. The German Accreditation Body, DAkkS (, accredits EQAT Phytoplankton for phytoplankton analysis according to DIN EN ISO 17025:2018 and as a provider of interlaboratory comparisons according to DIN EN ISO/IEC 17043:2010. With the help of the innovative reference counting chamber developed by EQAT Phytoplankton, systematic errors can be clearly distinguished from errors related to the detection of algae. This is done within the established work processes at the inverted microscope (Utermöhl technique).

The proficiency tests are based on the procedures described in the DIN EN 15204:2006 Guidance standard on the enumeration of phytoplankton using inverted microscopy (Utermöhl technique) and in DIN EN 16695:2015 Water quality - Guidance on the estimation of phytoplankton biovolume.

Design of our EQAT scheme

The EQAT design is focused on the application of the Utermöhl method using the inverted microscope and consists of three components. Components 1 and 2 are methodological, focussing on the enumeration and biovolume calculation and component 3 is taxonomic in nature.

Learn more

Procedure of our EQAT scheme

The EQAT scheme is divided into 9 phases, the status of which can be viewed on-line on our website. With the announcement of the EQAT scheme, the planned time schedule is communicated to the participants.

Learn more

Requirements for participation, costs and evaluation

Only laboratories that have the personnel and equipment required for the EQAT proficiency test phytoplankton can participate in our scheme. Each participant in the EQAT scheme requires an individual registration.

Learn more

About the organiser

The EQAT phytoplankton proficiency tests are an activity of the Landestalsperrenverwaltung des Freistaates Sachsen (LTV). 

Learn more


Since 2005, the evaluation of the results has been carried out in accordance with DIN 38402 – 45: 2014 using robust statistical methods.

Learn more


Show your colleagues and clients that you participate in the EQAT proficiency test phytoplankton!

Learn more