ISO 9308-1-2014 PDF

Full title and description

ISO 9308-1:2014 — Water quality — Enumeration of Escherichia coli and coliform bacteria — Part 1: Membrane filtration method for waters with low bacterial background flora. Specifies a membrane-filtration procedure using chromogenic coliform agar (CCA) to enumerate E. coli and coliform bacteria in waters with low background flora (for example drinking water, disinfected pool water and finished water from treatment plants).

Abstract

ISO 9308-1:2014 defines a quantitative membrane-filtration method based on growth on chromogenic coliform agar and calculation of colony counts. The method is intended for waters expected to produce fewer than about 100 total colonies on CCA; it can reliably enumerate E. coli and coliforms in low-background waters but is not suitable for surface waters and other samples with heavy background growth. Some E. coli strains that are β‑D‑glucuronidase negative (e.g., certain O157 strains) will not be detected as E. coli by this method and will appear as coliforms.

General information

• Status: Published.
• Publication date: September 2014 (ISO 9308-1:2014).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 07.100.20 — Microbiology of water.
• Edition / version: Edition 3 (2014); amended by ISO 9308-1:2014/Amd 1:2016.
• Number of pages: 10 pages (main document).

Scope

Specifies a membrane-filtration enumeration method for Escherichia coli and coliform bacteria in waters with low bacterial background flora. The method uses filtration of measured sample volumes, placement of the membrane on chromogenic coliform agar and incubation to obtain countable colonies; it is intended for waters that give fewer than about 100 total colonies on CCA and is not suitable for surface waters, shallow wells or other matrices with heavy interfering background flora.

Key topics and requirements

• Principle: membrane filtration of defined sample volumes, culture on chromogenic coliform agar (CCA) and enumeration of characteristic colonies for E. coli and coliform bacteria.
• Performance expectations: intended for low-background waters (target ≲100 total colonies on CCA) and includes provisions for performance testing of the chromogenic medium.
• Incubation and interpretation: amended guidance sets incubation of the membrane on CCA at 36 ± 2 °C for 21–24 h (see Amendment 1:2016 for the specified incubation regime and performance check details).
• Limitations: chromogenic detection relies on enzyme reactions (β‑D‑glucuronidase and β‑D‑galactosidase); some E. coli strains that are β‑D‑glucuronidase negative (e.g., certain enterohaemorrhagic O157 strains) may not be identified as E. coli and will instead appear as coliforms.
• Quality and reporting: method specifies controls, colony-count calculation (CFU per 100 ml), handling of non-countable plates and reporting conventions required for laboratory quality assurance.

Key method facts and amendment details taken from the ISO publication and Amendment 1 (2016).

Typical use and users

Routine microbiological testing laboratories, water utilities, drinking-water treatment operators, public-health agencies and regulatory bodies use ISO 9308-1:2014 for compliance monitoring and routine quality control of treated and distribution drinking waters, pool waters and other low-background water matrices. Environmental laboratories may instead select other parts of the ISO 9308 series when analysing surface or high-background waters.

Related standards

ISO 9308 is a multipart series. Notable related parts include ISO 9308-2:2012 (Most Probable Number method for enumeration by liquid enrichment) and ISO 9308-3:1998 (miniaturized MPN method for surface and waste waters). Work on additional parts (for example a membrane-filtration method tailored to waters with high background bacteria) has been progressed as drafts in the ISO committee.

Keywords

ISO 9308-1, water quality, Escherichia coli, coliform bacteria, membrane filtration, chromogenic coliform agar (CCA), enumeration, drinking water, microbiology, CCA, β‑D‑glucuronidase.

FAQ

Q: What is this standard?

A: ISO 9308-1:2014 is an international standard that specifies a membrane-filtration method using chromogenic coliform agar to enumerate E. coli and coliform bacteria in waters with low bacterial background.

Q: What does it cover?

A: It covers sampling considerations for low-background waters, membrane-filtration procedure, culture on chromogenic coliform agar, incubation and colony interpretation rules, limitations of the method and reporting of results (CFU per unit volume). The standard was amended in 2016 to clarify incubation/performance details.

Q: Who typically uses it?

A: Accredited microbiology laboratories, drinking-water utilities, pool operators, regulatory agencies and environmental testing services when analysing treated or distribution waters and other low-background matrices.

Q: Is it current or superseded?

A: ISO 9308-1:2014 is the current published edition (Edition 3, published September 2014) and has an Amendment 1 issued in 2016; it supersedes the 2000 edition. Users should check their national adoption/corrigenda and any later ISO committee activity for updates.

Q: Is it part of a series?

A: Yes — ISO 9308 is a multipart series on enumeration of E. coli and coliforms. Related parts include ISO 9308-2 (Most Probable Number method) and ISO 9308-3 (miniaturized MPN for surface/waste waters); additional parts or drafts address methods for high-background waters.

Q: What are the key keywords?

A: Escherichia coli, coliform, membrane filtration, chromogenic coliform agar, CCA, enumeration, drinking water, microbiology, ISO 9308-1.