ISO 7704-2023 PDF

Full title and description

St ISO 7704-2023 — Water quality — Requirements for the performance testing of membrane filters used for direct enumeration of microorganisms by culture methods. This international standard specifies requirements and test methods to assess the performance of membrane filters intended for retention followed by direct counting of microorganisms on solid media or media-containing devices (for example, absorbent pads).

Abstract

ISO 7704:2023 (2nd edition) defines how to perform and document performance testing of membrane filters used for direct enumeration of microorganisms by culture methods. It covers test design, preparations of test organisms, apparatus and media requirements, inoculation and incubation procedures, colony counting, calculation and interpretation of results, and documentation. The standard is intended to demonstrate the suitability of the complete system (membrane filter plus culture medium and filtration step) for microbiological analysis of various water types and to provide reproducible, traceable test outcomes for manufacturers and laboratories.

General information

• Status: Published (International Standard).
• Publication date: January 2023 (2nd edition, 2023‑01).
• Publisher: ISO — International Organization for Standardization.
• ICS / categories: 07.100.20 (Microbiology of water / Water quality).
• Edition / version: Edition 2 (2023).
• Number of pages: 36 pages.

Scope

This document specifies requirements for performance testing of membrane filters used for retention followed by direct enumeration of specific microorganisms by culture methods. It applies to membrane filters used for direct counting on solid media or on devices containing media (for example, absorbent pads). It is not applicable to membrane filters used for concentration-and-elution methods or for qualitative-only assays. The tests are applicable to membrane filters intended for microbiological analysis of various water types, including drinking and bottled water (low expected microbial counts) and waters with higher expected microbial loads (surface water, process water).

Key topics and requirements

• System suitability: demonstration of the whole analytical system (membrane filter + culture medium + filtration step).
• Definitions and terminology for performance testing, test microorganisms and sampling/replicates.
• Apparatus, glassware, culture media and diluents required for testing.
• Preparation and standardization of test microorganism suspensions and reference counts.
• Batch testing and supplementary testing procedures, including diagrammatic guidance for batch tests.
• Procedures for inoculation, incubation, colony counting, calculations and expression of results.
• Requirements for demonstrating absence of microbial contamination on unused filters.
• Data recording, test-report content, traceability and documentation requirements.
• Informative examples and annexes: test-record cards, examples of quantitative and qualitative supplementary testing.

Typical use and users

Primary users are membrane filter manufacturers (for product performance verification) and microbiological laboratories (internal validation and acceptance testing). Regulatory laboratories, water utilities, bottled-water producers, environmental testing labs and quality-control departments in water-related industries will also use the standard to verify filter performance for routine monitoring and method validation.

Related standards

Standards and documents frequently referenced alongside ISO 7704:2023 include ISO 8199 (general guidance and statistical methods for microbiology of water), ISO 11133 (preparation, production, storage and performance testing of culture media), the previous edition ISO 7704:1985 (superseded), and the corresponding CEN adoption EN ISO 7704:2023. ISO/TC 147/SC 4 (Microbiological methods) oversaw preparation of the standard in cooperation with CEN/TC 230.

Keywords

membrane filter, performance testing, water quality, direct enumeration, microbiology, culture methods, membrane filtration, system suitability, batch testing, productivity testing, absorbent pads

FAQ

Q: What is this standard?

A: ISO 7704:2023 is an international standard that specifies requirements and test methods for performance testing of membrane filters used for retention and direct enumeration of microorganisms by culture methods in water analysis.

Q: What does it cover?

A: It covers scope and terminology, apparatus and media requirements, preparation of test microorganisms, procedures for inoculation and incubation, counting and calculation of results, absence-of-contamination testing, batch and supplementary testing, and documentation and reporting of results.

Q: Who typically uses it?

A: Membrane filter manufacturers, environmental and water microbiology laboratories, regulatory and quality-control laboratories, bottled-water and water utility testing teams, and laboratories validating membrane-filtration methods.

Q: Is it current or superseded?

A: ISO 7704:2023 is the current (2nd) edition published in January 2023. It cancels and replaces ISO 7704:1985.

Q: Is it part of a series?

A: It is part of the body of ISO standards for water microbiology maintained by ISO/TC 147/SC 4 and is frequently used together with related standards such as ISO 8199 and ISO 11133; it has also been adopted as EN ISO 7704:2023 for CEN members.

Q: What are the key keywords?

A: membrane filter, water quality, direct enumeration, microbiology, culture methods, performance testing, membrane filtration, system suitability.