Water quality - Enumeration of culturable micro-organisms - Colony count by inoculation in a nutrient agar culture medium (ISO 6222:1999)

This European Standard specifies a method for the enumeration of culturable micro-organisms in water by counting the colonies formed in a nutrient agar culture medium after aerobic incubation at 36 °C and 22 °C. The method is intended to measure the operational efficiency of the treatment process of public drinking water supplies and for general application to all types of water. It is particulary applicable to the examination of water intended for  human consumption, including water in closed containers and to natural mineral waters.

Wasserbeschaffenheit - Quantitative Bestimmung der kultivierbaren Mikroorganismen - Bestimmung der Koloniezahl duch Einimpfen in ein Nähragarmedium (ISO 6222:1999)

Diese Europäische Norm beschreibt ein Verfahren für den quantitativen Nachweis von kultivierbaren Mikroorganismen im Wasser durch Zählung der Kolonien, die sich auf Nähragar nach aerober Inkubation bei 36 °C und 22 °C bilden. Das Verfahren ist anwendbar zur Beurteilung der Leistungsfähigkeit des Aufbereitungsprozesses der öffentlichen Trinkwasserversorgungen und fu(r allgemeine Anwendungen für alle Arten von Wasser. Es ist besonders geeignet für die Untersuchung von Wasser für den menschlichen Gebrauch, einschließlich Wasser in geschlossenen Behältnissen und natu(rliche Mineralwa(sser.

Qualité de l'eau - Dénombrement des micro-organismes revivifiables - Comptage des colonies par ensemencement dans un milieu de culture nutritif gélosé (ISO 6222:1999)

La présente norme internationale spécifie une méthode de dénombrement des micro-organismes revivifiables présents dans l'eau par comptage des colonies se formant dans un milieu de culture nutritif gélosé après incubation en aérobiose à 36 °C et 22 °C. La méthode vise à mesurer l'efficacité de fonctionnement du procédé de traitement des alimentations publiques en eau potable et, plus généralement de tous les types d'eau. Elle est plus particulièrement applicable à l'analyse des eaux destinées à la consommation humaine, y compris des eaux en récipients fermés et des eaux minérales naturelles.

Kakovost vode – Ugotavljanje števila mikroorganizmov, sposobnih tvorbe kolonij - Štetje kolonij z nasajanjem v hranljivi agar (ISO 6222:1999)

General Information

Status
Published
Publication Date
31-Oct-1999
Technical Committee
KAV - Water quality
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Nov-1999
Due Date
01-Nov-1999
Completion Date
01-Nov-1999
Directive
Slovenian Regulation2004-01-0865 - Pravilnik o pitni vodi
 

Slovenian RegulationTP262 - Uredba o pitni vodi

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SIST EN ISO 6222:1999

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Effective Date
01-Nov-1999
Effective Date
09-Feb-2026
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28-Jan-2026
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28-Jan-2026
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28-Jan-2026
Effective Date
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Effective Date
28-Jan-2026

Overview

SIST EN ISO 6222:1999 specifies a standardized method for the enumeration of culturable micro-organisms in water, using colony count after aerobic incubation in a nutrient agar culture medium at 36 °C and 22 °C. This European Standard is a critical tool for assessing water quality, particularly the operational efficiency of water treatment processes and the safety of water intended for human consumption. The method is broadly applicable to all types of water, including public drinking water, bottled water, and natural mineral waters.

By employing a culture-based approach, the standard enables laboratories and water suppliers to detect and quantify aerobic micro-organisms, serving as an essential component of routine water quality monitoring and hygiene assurance.

Key Topics

  • Enumeration of Micro-organisms: A well-defined protocol for counting culturable bacteria, yeasts, and moulds in water samples by inoculation and growth on nutrient agar.
  • Incubation Temperature Range: Analysis is performed at two temperatures: 36 °C to identify organisms suited to human body temperature, and 22 °C, which is optimal for environmental micro-organisms.
  • Sample Handling: Recommendations for water sample collection, preservation, and timely analysis to minimize contamination and changes in micro-organism counts.
  • Reporting: Results are expressed as colony-forming units per millilitre (cfu/ml), providing a quantitative measure of microbiological water quality.
  • Laboratory Practices: Guidance on media preparation, dilution protocols, and counting techniques to ensure reproducibility and reliability.

Applications

SIST EN ISO 6222:1999 is widely used in the following sectors:

  • Public Drinking Water Monitoring: Routine examination of municipal water supplies to verify the effectiveness of treatment processes such as filtration and disinfection, and to assess the integrity of distribution systems.
  • Bottled and Mineral Water Quality Control: Ensuring compliance with microbiological standards for water intended for human consumption, including water in closed containers and natural mineral waters.
  • Industrial and Environmental Hygiene: Checking water purity in food and beverage production to prevent contamination, as well as monitoring surface and groundwater as part of environmental protection programs.
  • Early Warning and Incident Investigation: Identifying abnormal increases in micro-organism levels which may indicate contamination or failure in water treatment systems, prompting further investigation and corrective action.

The method is particularly valuable due to its simplicity, versatility, and established reliability in detecting sudden changes in bacterial counts that can signal potential pollution or hygiene lapses.

Related Standards

Organisations implementing SIST EN ISO 6222:1999 may also refer to the following key standards for complementary guidance on water microbiology and laboratory analysis:

  • EN ISO 3696: Water for analytical laboratory use - Specification and test methods
  • EN ISO 5667-3: Water quality - Sampling - Guidance on the preservation and handling of samples
  • EN 25667-2: Water quality - Sampling - Guidance on sampling techniques
  • ISO 6887: Microbiology - General guidance for the preparation of dilutions for microbiological examinations
  • ISO 8199: Water quality - General guide to the enumeration of micro-organisms by culture

These standards support the correct application, validation, and reporting of microbiological analyses and help laboratories maintain compliance with international best practices for water quality assessment.

SIST EN ISO 6222:1999 thus forms a fundamental part of comprehensive water safety and monitoring programs, supporting public health and regulatory compliance through robust and reproducible microbiological testing.

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Frequently Asked Questions

SIST EN ISO 6222:1999 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "Water quality - Enumeration of culturable micro-organisms - Colony count by inoculation in a nutrient agar culture medium (ISO 6222:1999)". This standard covers: This European Standard specifies a method for the enumeration of culturable micro-organisms in water by counting the colonies formed in a nutrient agar culture medium after aerobic incubation at 36 °C and 22 °C. The method is intended to measure the operational efficiency of the treatment process of public drinking water supplies and for general application to all types of water. It is particulary applicable to the examination of water intended for human consumption, including water in closed containers and to natural mineral waters.

This European Standard specifies a method for the enumeration of culturable micro-organisms in water by counting the colonies formed in a nutrient agar culture medium after aerobic incubation at 36 °C and 22 °C. The method is intended to measure the operational efficiency of the treatment process of public drinking water supplies and for general application to all types of water. It is particulary applicable to the examination of water intended for human consumption, including water in closed containers and to natural mineral waters.

SIST EN ISO 6222:1999 is classified under the following ICS (International Classification for Standards) categories: 07.100.20 - Microbiology of water. The ICS classification helps identify the subject area and facilitates finding related standards.

SIST EN ISO 6222:1999 has the following relationships with other standards: It is inter standard links to SIST ISO 6222:1997, SIST ISO 8199:1997, SIST EN ISO 5667-1:2023, SIST EN ISO 5667-3:2024, SIST EN ISO 3696:1998, SIST EN ISO 4540:1999, SIST EN ISO 683-17:2023, SIST EN ISO 16120-3:2011, SIST EN 71-20:2026, SIST EN ISO 683-1:2018, SIST EN ISO 683-5:2021, SIST EN ISO 683-7:2024, SIST EN ISO 13680:2025, SIST EN ISO 11296-9:2023, SIST EN ISO 16120-1:2011. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.

SIST EN ISO 6222:1999 is associated with the following European legislation: EU Directives/Regulations: 2004-01-0865, 2015-01-2455, TP262. When a standard is cited in the Official Journal of the European Union, products manufactured in conformity with it benefit from a presumption of conformity with the essential requirements of the corresponding EU directive or regulation.

SIST EN ISO 6222:1999 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.

Standards Content (Sample)


SLOVENSKI STANDARD
01-november-1999
1DGRPHãþD
SIST ISO 6222:1997
Kakovost vode – Ugotavljanje števila mikroorganizmov, sposobnih tvorbe kolonij -
Štetje kolonij z nasajanjem v hranljivi agar (ISO 6222:1999)
Water quality - Enumeration of culturable micro-organisms - Colony count by inoculation
in a nutrient agar culture medium (ISO 6222:1999)
Wasserbeschaffenheit - Quantitative Bestimmung der kultivierbaren Mikroorganismen -
Bestimmung der Koloniezahl duch Einimpfen in ein Nähragarmedium (ISO 6222:1999)
Qualité de l'eau - Dénombrement des micro-organismes revivifiables - Comptage des
colonies par ensemencement dans un milieu de culture nutritif gélosé (ISO 6222:1999)
Ta slovenski standard je istoveten z: EN ISO 6222:1999
ICS:
07.100.20 Mikrobiologija vode Microbiology of water
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 6222
Second edition
1999-05-15
Water quality — Enumeration of culturable
micro-organisms — Colony count by
inoculation in a nutrient agar culture
medium
Qualité de l'eau — Dénombrement des micro-organismes revivifiables —
Comptage des colonies par ensemencement dans un milieu de culture nutritif
gélosé
A
Reference number
ISO 6222:1999(E)
ISO 6222:1999(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide
federation of national standards bodies (ISO member bodies). The work of
preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which
a technical committee has been established has the right to be represented
on that committee. International organizations, governmental and non-
governmental, in liaison with ISO, also take part in the work. ISO
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in
the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
Attention is drawn to the possibility that some of the elements of this
International Standard may be the subject of patent rights. ISO shall not be
held responsible for identifying any or all such patent rights.
International Standard ISO 6222 was prepared by the European
Committee for Standardization (CEN) in collaboration with ISO Technical
Committee TC 147, Water quality, Subcommittee SC 4, Microbiological
methods, in accordance with the Agreement on technical cooperation
between ISO and CEN (Vienna Agreement).
Throughout the text of this document, read “.this European Standard.” to
mean “.this International Standard.”.
This second edition cancels and replaces the first edition (ISO 6222:1988),
which has been technically revised.
©  ISO 1999
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet iso@iso.ch
Printed in Switzerland
ii
©
ISO
ISO 6222:1999(E)
Foreword
The text of EN ISO 6222:1999 has been prepared by Technical Committee CEN/TC 230 "Water analysis", the secretariat
of which is held by DIN, in collaboration with Technical Committee ISO/TC 147 "Water quality".
This European Standard shall be given the status of a national standard, either by publication of an identical text or by
endorsement, at the latest by November 1999, and conflicting national standards shall be withdrawn at the latest by
November 1999.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries
are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France,
Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and
the United Kingdom.
Introduction
Waters of all kinds invariably contain a variety of micro-organisms derived from various sources, such as soil and
vegetation, and estimation of the overall numbers provide useful information for the assessment and surveillance of water
quality. Separate counts are usually made of the micro-organisms which are able to grow and form colonies on nutrient
agar media at 36 °C and 22 °C.
Colony counts are useful for assessing the integrity of ground water sources and the efficiency of water treatment
processes such as coagulation, filtration and disinfection and provide an indication of the cleanliness and integrity of the
distribution system. They can also be used to assess the suitabillty of a supply for the preparation of food and drink,
where the water supply should contain few micro-organisms to avoid contaminating the product with spoilage organisms.
The main value of colony counts lies in the detection of changes from those expected, based on frequent, long term
monitoring. Any sudden increase in the count can be an early warning of serious pollution and calls for immediate
investigation.
1 Scope
This European Standard specifies a method for the enumeration of culturable micro-organisms in water by counting the
colonies formed in a nutrient agar culture medium after aerobic incubation at 36 °C and 22 °C.
The method is intended to measure the operational efficiency of the treatment process of public drinking water supplies
and for general application to all types of water. It is particularly applicable to the examination of water
...