Clean water samples are generally taken for microbiological analysis. Water intended for human consumption must not harm consumer health, so it must be free of all pathogenic microorganisms. 

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Samples for microbiological analyses 

There are two main categories of samples: 

• Drinking water samples for analysis: these samples aim to check the conformity of the water consumed, in accordance with the Decree of 21 January 2010 (D1-type analysis), or to ensure that there are no health risks, as per the Decree of 1 February 2010 (legionella). These samples are collected from taps or showers in cold or hot water networks. 
• Samples from cooling towers: these samples are mainly taken to comply with regulations, as per the Decree of 14 December 2013. 

These samples are all taken sporadically while observing a number of rules and precautions to avoid contaminating the collected sample 

They are taken by CTC sampling technicians according to COFRAC accreditation requirements. 

The frequency of these checks depends on the classification of the facility or its category, as well as on the results of previous measurements. In general, an annual check is carried out, whereas for the cooling towers, this check may be monthly in certain cases. 

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Structures concerned 

Two types of structure must undergo sampling for microbiological analysis: 

• Collective domestic hot water production, storage and distribution installations that supply healthcare establishments, social and medical institutions, prisons, hotels, tourist accommodation, campsites and other establishments open to the public. 
• Industrial facilities with a wet cooling system. 

 

Why conduct sampling ? 

Drinking water analysis  

Drinking water is sampled and analysed to detect the presence of microorganisms (bacteria, viruses and parasites). This verifies the effectiveness of the disinfection process and ensures that the water is safe for consumers. 

The presence of microorganisms in drinking water can pose a short-term risk to consumers, although the clinical presentation of the resulting pathologies is usually benign for the general population (gastrointestinal problems, diarrhoea, etc.). 

Legionella analysis 

Legionella sampling and analysis is carried out to detect the presence of legionella in facilities where these bacteria can proliferate, including: 

• Domestic cold water systems 
• Domestic hot water systems 
• Wet cooling systems or cooling towers 
• Water features and natural water 

The Decree of 11 January 2007, regarding the health inspection sampling and analysis programme for water supplied by a distribution network, sets out the sampling frequency: 

 

Toxicity assessment (Daphnia) 

This toxicity assessment service analyses effluents in accordance with the Water Framework Directive and the decrees of 21 December 2007 and 20 March 2015. 

Ecotoxicology focuses on the impact of toxic pollutants, such as pesticides and polychlorinated biphenyls (PCB), on ecosystems. 

Using Daphnia can rapidly provide data on the toxicity of the different pollutants present in water, particularly those capable of inhibiting the development or activity of aquatic organisms. 

This test highlights acute toxicity, i.e. short-term toxicity. 

The results obtained are essential for determining the toxicity concentration in equitox per cubic metre. This measurement indicates the amount of toxicity which, in 1 m³ of water, will immobilise 50% of the Daphnia after 24 hours. 

It is an essential value for establishing how the water pollution charge will be calculated. 

 

 

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