DIN EN ISO 5667-3:2026-11 - Draft

Preserve water samples correctly and keep them stable until analysis

The DIN EN ISO 5667-3 specifies requirements for the preservation, handling, storage and transport of water samples. It helps laboratories, sampling facilities, environmental authorities and water suppliers ensure the quality and integrity of water samples between sampling and analysis. The standard is part of the ISO 5667 “Water quality — Sampling” series and provides a key basis for reliable analytical results.

What is DIN EN ISO 5667-3 about?

The standard defines general requirements for the preservation and handling of water samples for physicochemical, chemical, microbiological, hydrobiological and radiochemical examinations. It focuses on selecting suitable sample containers, preservatives, storage conditions and maximum storage times, as well as requirements for sample transport, sample labelling and sample receipt at the laboratory. In addition, the standard describes procedures for safeguarding sample integrity and includes comprehensive tables of recommended preservation and storage conditions for a wide range of analytes.

Topics covered

• Preservation and handling of water samples
• Selection and pretreatment of sample containers
• Filtration, sample labelling and sample storage
• Sample transport and chain of custody
• Preservation procedures for inorganic and organic analytes
• Preservation of microbiological and hydrobiological samples
• Requirements for radiochemical examinations
• Maximum storage times and storage conditions
• Validated and established preservation procedures

Practical relevance

Between sampling and analysis, water samples may change as a result of biological, chemical or physical processes. DIN EN ISO 5667-3 helps users avoid sample losses, substance transformations and distortions of analytical results. It therefore provides an important basis for robust test results in water analysis, environmental monitoring and drinking water surveillance.

The detailed specifications for preservatives, storage conditions, maximum storage times and sample containers are particularly relevant, as these factors directly affect the quality of analytical results. The standard is frequently used in conjunction with other parts of the ISO 5667 series and plays a central role in the quality management of water analysis.

Changes compared with DIN EN ISO 5667-3:2019-07

The 2024 edition has been technically revised and expanded. The most important changes include:

• Addition of references to ISO/TS 5667-25 for validating storage times and preservation procedures
• Addition of a flowchart for selecting preservation and storage procedures
• Division of the previous table on preservation techniques into separate tables for inorganic and organic analytes
• New table for microbiological examination
• Addition of water types and explanatory terms to the preservation tables
• Updated normative references and bibliography

Target audience

• Water testing laboratories and test laboratories
• Environmental and water authorities
• Drinking water suppliers
• Water analysis professionals
• Sampling service providers
• Environmental assessors and experts
• Operators of water and wastewater facilities
• Quality managers in environmental and water analysis

Conclusion

The DIN EN ISO 5667-3 provides the central basis for the preservation, storage and handling of water samples. With its detailed specifications for sample containers, storage conditions, maximum storage times and preservation procedures, it helps ensure robust analytical results and a high standard of quality in water analysis.