Water is elixir for life but safe drinking water for mankind is a big challenge of 21st century, because many people's not getting safe and clean water supply and dying of diarrheal disease. So, to encounter this global problem, the potability or suitability to drink water is analyzed by the microbiological examinations which have been globally approved.
The microbiological analysis of water is mainly relies on the concept of indicator microorganisms, mainly bacteria under the stipulated time and control and has been adopted in many legislations worldwide. Because the risk of disease outbreaks correlate with the incidence of fecal contamination, faecal bacteria used as potential indicators of faecal contamination and hence the possible presence of pathogens.
"Indicator" microorganisms used to assess the microbiological quality of drinking water as well as correlation with some of other bacteria and their relationship with pathogens which causing disease like salmonella cause typhoid.
The most widely used and has been accepted indicator are coliform (total coliform), faecal coliform or thermotolerant coliform, Escherichia coli, enterococci (faecal streptococci or intestinal enterococci) and bacteriophages. Some of the alternative indictors are also used which includes Sulfite-reducing clostridia, Pseudomonas spp. And Heterotrophic plate counts.
Following criteria has been approved which are fulfilled by the indicator microorganisms are given hereunder:
a) Organism should be present whenever enteric pathogens are present and absent whenever pathogens are absent.
b) Organism present at a density should have some constant direct relationship with density of pathogens.
c) Organism should be useful for the analysis of all kind of environmentally polluted media.
d) Organism should not grow in the polluted water.
e) Organism should survive in the environment as long as possible.
f) Organism should be nonpathogenic to human and easily recognizable.
In summary, we can say that the indicator organism should be the indicator of following:
a) Faecal pollution.
b) Presence of domestic sewage.
c) Presence of pathogens causing disease.
World health organization (WHO) is very active this field and recommended the water safety plans to ensure the safe drinking water supply, which is found in the WHO technical guidance documents and is also available in WHO directory.
Microbiological analysis of drinking water supply should be the norm everywhere, so that a clean and safe drinking water can be accessible to all. The microbiological identification and enumeration of indicators are too slow therefore are not suitable. Although there is no universal indicator available, research is ongoing to search a ideal indicator for the presence and behavior of some newly reported causative agents of water-borne disease than traditional indicators.
About Author / Additional Info:
Department of Environmental Microbiology
Babasaheb Bhimrao Ambedkar (Central) University
Lucknow (U.P)- 226 025 India