Foreword
Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This document is developed in accordance with the rules given in GB/T 1.1-2020 Directives for standardization - Part 1: Rules for the structure and drafting of standardizing documents.
This document is Part 12 of GB/T 5750 Standard examination methods for drinking water. The following parts of GB/T 5750 have been issued:
——Part 1: General principles;
——Part 2: Collection and preservation of water samples;
——Part 3: Water analysis quality control;
——Part 4: Organoleptic and physical indices;
——Part 5: Inorganic nonmetallic indices;
——Part 6: Metal and metalloid indices;
——Part 7: Aggregate organic indices;
——Part 8: Organic indices;
——Part 9: Pesticides indices;
——Part 10: Disinfection by-products indices;
——Part 11: Disinfectants indices;
——Part 12: Microbiological indices;
——Part 13: Radiological indices.
This document replaces GB/T 5750.12-2006 Standard examination methods for drinking water - Microbiological parameters. In addition to structural adjustment and editorial changes, the following main technical changes have been made with respect to GB/T 5750.12-2006:
a) 6 examination methods have been added (see 4.2, 8.2, 9.2, 10.1, 10.2 and 11.1 hereof).
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.
This document was proposed by and is under the jurisdiction of the National Health Commission of the People's Republic of China.
The previous editions of this document are as follows:
——This document was firstly issued as GB/T 5750-1985 in 1985 and firstly revised as GB/T 5750.12-2006 in 2006;
——This is the second revision.
Introduction
The series of standards GB/T 5750 Standard examination methods for drinking water, as the recommended national standards for drinking water examination technology, are compatible with GB 5749 Standards for drinking water quality, and are also served as an important technical support of GB 5749. They provide examination methods for implementing GB 5749 and carrying out hygienic safety evaluation of drinking water.
GB/T 5750 consists of 13 parts.
——Part 1: General principles; It provides the basic principles and requirements for water quality examination.
——Part 2: Collection and preservation of water samples. It provides the basic principles, measures and requirements for water sample collection, preservation, management, transportation and sampling quality control.
——Part 3: Water analysis quality control. It provides quality control requirements and methods for water quality examination and testing laboratories.
——Part 4: Organoleptic and physical indices. It provides corresponding examination methods for organoleptic and physical indices.
——Part 5: Inorganic nonmetallic indices. It provides corresponding examination methods for inorganic nonmetallic indices.
——Part 6: Metal and metalloid indices. It provides corresponding examination methods for metal and metalloid indices.
——Part 7: Aggregate organic indices. It provides corresponding examination methods for aggregate organic indices.
——Part 8: Organic indices. It provides corresponding examination methods for organic indices.
——Part 9: Pesticides indices. It provides corresponding examination methods for pesticides indices.
——Part 10: Disinfection by-products indices. It provides corresponding examination methods for disinfection by-products indices.
——Part 11: Disinfectants indices. It provides corresponding examination methods for disinfectants indices.
——Part 12: Microbiological indices. It provides corresponding examination methods for microbiological indices.
——Part 13: Radiological indices. It provides corresponding examination methods for radiological indices.
Standard examination methods for drinking water - Part 12: Microbiological indices
1 Scope
This document describes the methods for determination of standard plate-count bacteria, total coliforms, thermotolerant coliform bacteria, Escherichia coli, Giardia, Cryptosporidium, Enterococcus and Clostridium perfringens in drinking water and water sources.
This document is applicable to the determination of microbiological indices in drinking water and water sources.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB 4789.28 National food safety standard - Food microbiological examination - Quality requirements for medium and reagents
GB/T 6682 Water for analytical laboratory use - Specification and test methods
GB 19489 Laboratories - General requirements for biosafety
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
standard plate-count bacteria
number of microbial colonies in 1mL of water sample after incubation for a certain period of time under certain conditions
3.2
total coliforms
a group of aerobic and facultative anaerobic non-spore-forming Gram-negative bacillus capable of fermenting lactose, producing acid and gas within 24h of incubation at 37℃
3.3
thermotolerant coliform bacteria
a group of aerobic and facultative anaerobic non-spore-forming Gram-negative bacillus capable of fermenting lactose, producing acid and gas within 24h of incubation at 44.5℃
3.4
Escherichia coli
a group of non-spore-forming Gram-negative brevibacterium capable of fermenting various sugars, producing acid and gas, flagellating all over the body and moving, which is usually found in the intestines and feces of humans and warm-blooded animals
3.5
Giardia
protozoan parasite found in water or other media, which can infect humans and cause diseases
Note: Giardia cysts are elliptical, with a length of 8μm~14μm and a width of 7μm~10μm. There are two nuclei in initial cysts, and four in mature cysts.
3.6
Cryptosporidium
protozoan parasite found in water or other media, which can infect humans and cause diseases
Note: Cryptosporidium oocysts are slightly elliptical and round, with a diameter of 4μm to 8μm. There are four nuclei in mature oocysts.
3.7
Enterococcus
a type of facultative anaerobic non-spore and non-capsule-forming Gram-positive cocci in pairs or in chains, belonging to Group D Streptococci, typically present in the intestines and feces of humans and warm-blooded animals
3.8
Clostridium perfringens
a type of anaerobic spore-forming Gram-positive bacilli capable of reducing sulfite, typically present in the intestines and feces of humans and warm-blooded animals
3.9
most probable number; MPN
number of target microorganisms present in a certain volume of samples, i.e., the most probable number of target microorganisms per unit volume, estimated based on the number of positive target microorganisms produced by incubation of a certain volume of samples with different dilutions, using the principle of statistics and according to the Poisson distribution
4 Standard plate-count bacteria
4.1 Plate counting method
4.1.1 Principle
After culturing 1mL of water sample on nutrient agar medium at 36℃±1℃ under aerobic conditions for 48h, the standard plate-count bacteria in 1mL of water sample can be determined.
4.1.2 Nutrient agar medium
4.1.2.1 Component
It can be prepared as follows:
a) Peptone 10.0g
b) Beef extract 3.0g
c) Sodium chloride 5.0g
d) Agar 10.0g~20.0g
e) Pure water 1,000mL
4.1.2.2 Preparation
Mix the above components, heat for dissolution, adjust the pH to 7.4~7.6, distribute into glass containers, carry out autoclaved sterilization at 121℃ for 20min, and store in refrigerator at 0℃~4℃.
Foreword I
Introduction III
1 Scope
2 Normative references
3 Terms and definitions
4 Standard plate-count bacteria
5 Total coliforms
6 Thermotolerant coliform bacteria
7 Escherichia coli
8 Giardia
9 Cryptosporidium
10 Enterococcus
11 Clostridium perfringens
Foreword
Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This document is developed in accordance with the rules given in GB/T 1.1-2020 Directives for standardization - Part 1: Rules for the structure and drafting of standardizing documents.
This document is Part 12 of GB/T 5750 Standard examination methods for drinking water. The following parts of GB/T 5750 have been issued:
——Part 1: General principles;
——Part 2: Collection and preservation of water samples;
——Part 3: Water analysis quality control;
——Part 4: Organoleptic and physical indices;
——Part 5: Inorganic nonmetallic indices;
——Part 6: Metal and metalloid indices;
——Part 7: Aggregate organic indices;
——Part 8: Organic indices;
——Part 9: Pesticides indices;
——Part 10: Disinfection by-products indices;
——Part 11: Disinfectants indices;
——Part 12: Microbiological indices;
——Part 13: Radiological indices.
This document replaces GB/T 5750.12-2006 Standard examination methods for drinking water - Microbiological parameters. In addition to structural adjustment and editorial changes, the following main technical changes have been made with respect to GB/T 5750.12-2006:
a) 6 examination methods have been added (see 4.2, 8.2, 9.2, 10.1, 10.2 and 11.1 hereof).
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.
This document was proposed by and is under the jurisdiction of the National Health Commission of the People's Republic of China.
The previous editions of this document are as follows:
——This document was firstly issued as GB/T 5750-1985 in 1985 and firstly revised as GB/T 5750.12-2006 in 2006;
——This is the second revision.
Introduction
The series of standards GB/T 5750 Standard examination methods for drinking water, as the recommended national standards for drinking water examination technology, are compatible with GB 5749 Standards for drinking water quality, and are also served as an important technical support of GB 5749. They provide examination methods for implementing GB 5749 and carrying out hygienic safety evaluation of drinking water.
GB/T 5750 consists of 13 parts.
——Part 1: General principles; It provides the basic principles and requirements for water quality examination.
——Part 2: Collection and preservation of water samples. It provides the basic principles, measures and requirements for water sample collection, preservation, management, transportation and sampling quality control.
——Part 3: Water analysis quality control. It provides quality control requirements and methods for water quality examination and testing laboratories.
——Part 4: Organoleptic and physical indices. It provides corresponding examination methods for organoleptic and physical indices.
——Part 5: Inorganic nonmetallic indices. It provides corresponding examination methods for inorganic nonmetallic indices.
——Part 6: Metal and metalloid indices. It provides corresponding examination methods for metal and metalloid indices.
——Part 7: Aggregate organic indices. It provides corresponding examination methods for aggregate organic indices.
——Part 8: Organic indices. It provides corresponding examination methods for organic indices.
——Part 9: Pesticides indices. It provides corresponding examination methods for pesticides indices.
——Part 10: Disinfection by-products indices. It provides corresponding examination methods for disinfection by-products indices.
——Part 11: Disinfectants indices. It provides corresponding examination methods for disinfectants indices.
——Part 12: Microbiological indices. It provides corresponding examination methods for microbiological indices.
——Part 13: Radiological indices. It provides corresponding examination methods for radiological indices.
Standard examination methods for drinking water - Part 12: Microbiological indices
1 Scope
This document describes the methods for determination of standard plate-count bacteria, total coliforms, thermotolerant coliform bacteria, Escherichia coli, Giardia, Cryptosporidium, Enterococcus and Clostridium perfringens in drinking water and water sources.
This document is applicable to the determination of microbiological indices in drinking water and water sources.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB 4789.28 National food safety standard - Food microbiological examination - Quality requirements for medium and reagents
GB/T 6682 Water for analytical laboratory use - Specification and test methods
GB 19489 Laboratories - General requirements for biosafety
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
standard plate-count bacteria
number of microbial colonies in 1mL of water sample after incubation for a certain period of time under certain conditions
3.2
total coliforms
a group of aerobic and facultative anaerobic non-spore-forming Gram-negative bacillus capable of fermenting lactose, producing acid and gas within 24h of incubation at 37℃
3.3
thermotolerant coliform bacteria
a group of aerobic and facultative anaerobic non-spore-forming Gram-negative bacillus capable of fermenting lactose, producing acid and gas within 24h of incubation at 44.5℃
3.4
Escherichia coli
a group of non-spore-forming Gram-negative brevibacterium capable of fermenting various sugars, producing acid and gas, flagellating all over the body and moving, which is usually found in the intestines and feces of humans and warm-blooded animals
3.5
Giardia
protozoan parasite found in water or other media, which can infect humans and cause diseases
Note: Giardia cysts are elliptical, with a length of 8μm~14μm and a width of 7μm~10μm. There are two nuclei in initial cysts, and four in mature cysts.
3.6
Cryptosporidium
protozoan parasite found in water or other media, which can infect humans and cause diseases
Note: Cryptosporidium oocysts are slightly elliptical and round, with a diameter of 4μm to 8μm. There are four nuclei in mature oocysts.
3.7
Enterococcus
a type of facultative anaerobic non-spore and non-capsule-forming Gram-positive cocci in pairs or in chains, belonging to Group D Streptococci, typically present in the intestines and feces of humans and warm-blooded animals
3.8
Clostridium perfringens
a type of anaerobic spore-forming Gram-positive bacilli capable of reducing sulfite, typically present in the intestines and feces of humans and warm-blooded animals
3.9
most probable number; MPN
number of target microorganisms present in a certain volume of samples, i.e., the most probable number of target microorganisms per unit volume, estimated based on the number of positive target microorganisms produced by incubation of a certain volume of samples with different dilutions, using the principle of statistics and according to the Poisson distribution
4 Standard plate-count bacteria
4.1 Plate counting method
4.1.1 Principle
After culturing 1mL of water sample on nutrient agar medium at 36℃±1℃ under aerobic conditions for 48h, the standard plate-count bacteria in 1mL of water sample can be determined.
4.1.2 Nutrient agar medium
4.1.2.1 Component
It can be prepared as follows:
a) Peptone 10.0g
b) Beef extract 3.0g
c) Sodium chloride 5.0g
d) Agar 10.0g~20.0g
e) Pure water 1,000mL
4.1.2.2 Preparation
Mix the above components, heat for dissolution, adjust the pH to 7.4~7.6, distribute into glass containers, carry out autoclaved sterilization at 121℃ for 20min, and store in refrigerator at 0℃~4℃.
Contents of GB/T 5750.12-2023
Foreword I
Introduction III
1 Scope
2 Normative references
3 Terms and definitions
4 Standard plate-count bacteria
5 Total coliforms
6 Thermotolerant coliform bacteria
7 Escherichia coli
8 Giardia
9 Cryptosporidium
10 Enterococcus
11 Clostridium perfringens
