Microbiological monitoring of water

Water is an essential element for the development of life: the body of an adult human being is 60% water. Because of its vital nature, the water used in human activities must be of good sanitary quality to avoid the onset of water-borne pathologies.

Microorganisms of human or specifically environmental origin (bacteria, yeasts, filamentous fungi, parasites and viruses) present in the environment belong to the opportunistic and pathogenic species for humans. Their ubiquitous presence, the result of natural biological activity, means that they can be found in all types of water, including drinking water, where the causes of germ introduction into a network are most often the result of a lack of resource protection, combined with faulty or non-existent water treatment, or a fault in the distribution circuit. Environmental contamination varies qualitatively and quantitatively from one type of water to another, and within the same type, according to the environment and its layout, as well as the survival capacity of micro-organisms. In addition, the identification of certain environmental sources potentially responsible for nosocomial infections (legionellosis) makes it essential to control the environment in order to protect the population.

Pathogenic germs, capable of causing disease, mostly come from human or animal dejecta. The main waterborne infections observed in France are digestive disorders (gastroenteritis). Typhoid, paratyphoid, viral hepatitis and dysentery are more serious, but much rarer. The contamination of water (drinking water, swimming in natural waters or pools, hot water, etc.) by pathogenic germs can lead to isolated cases of infection, or even epidemic situations in the case of heavily contaminated water. However, the presence of human pathogens in water does not mean that people in contact with the water will become infected, despite the immediate effects on health. Infection requires the combination of several factors linked to the micro-organism (nature and concentration of pathogenic germs present in the water), the route of transmission (quantity of water ingested, inhalation), and the host's receptivity (general state of health of individuals, sensitivity, age, immunodeficiency).

Providing the population with water of good sanitary quality is an essential and ongoing concern for the health authorities (the Ministry of Health and the Regional Health Agencies), because of the immediate potential risks involved. Microbiological water quality is defined as the state of water characterized by the presence of micro-organisms (viruses, bacteria, protozoa, etc.) that can pose a health risk of varying degrees. Its control is based on the monitoring and control of microbiological parameters, the identification of risk factors...