EN ISO 7704:2023 PDF

Overview

EN ISO 7704:2023 (ISO 7704:2023) - published by CEN/ISO - defines requirements for the performance testing of membrane filters used for the retention and direct enumeration of microorganisms by culture methods. The standard applies to membrane filters used for direct counting on solid media or on devices containing media (e.g., absorbent pads). It is explicitly not intended for filters used for concentration-and-elution methods or for purely qualitative assays.

Key topics and technical requirements

• Scope of applicability
  • Designed for microbiological analysis of various water types: drinking water, bottled water, surface water, and process water (low and higher expected microbial loads).
• System suitability
  • Emphasizes demonstration of the whole system (membrane filter + culture medium + filtration step) for performance testing.
• Test design and content
  • Definitions and terminology for performance testing and test microorganisms.
  • Requirements for apparatus, culture media and diluents, and preparation of standardized test suspensions.
  • Sampling of membrane filters and handling of replicates.
  • Detailed procedures including inoculation techniques (spread-plate and membrane filtration), incubation, colony counting and interpretation.
  • Tests for absence of microbial contamination on filters.
• Data, calculations and documentation
  • Calculation, expression and interpretation of results; requirements for test reports and traceability.
• Annexes
  • Includes a normative diagram for batch testing and informative examples: test-record cards, quantitative and qualitative supplementary testing, and practical examples for end users.

Applications and users

• Primary users
  • Manufacturers of membrane filters - to validate product performance and provide required information to customers.
  • Microbiological laboratories - to qualify filters for routine testing or to supply validated filters to end users.
• Practical applications
  • Quality control and validation of membrane filtration systems used in water microbiology, regulatory monitoring, bottled water testing, environmental surveillance, and industrial process water testing.
  • Ensuring that filters and media reliably retain and permit enumeration of target microorganisms for regulatory compliance and laboratory QA/QC.

Related standards

• Developed by ISO/TC 147 (Water quality) in collaboration with CEN/TC 230 (Water analysis). It replaces the earlier ISO 7704:1985 and complements other ISO/CEN microbiological water analysis standards. Users should consult related standards from ISO/TC 147 and CEN/TC 230 for specific test methods and organism-specific procedures.

Keywords: EN ISO 7704:2023, ISO 7704:2023, water quality, membrane filters, performance testing, direct enumeration, culture methods, microbiological analysis, drinking water testing.