S Malhotra, U Arora, P Devi
bacteriological examination, eijkman test, presumptive coliform count
S Malhotra, U Arora, P Devi. How safe is the safe water supply?. The Internet Journal of Microbiology. 2008 Volume 7 Number 1.
A total of 1200 drinking water samples from various water sources in Amritsar district, were analyzed to assess bacteriological quality of water. Presumptive coliform count by multiple tube test was done. The study revealed that 570 (47.5%) samples were unfit for human consumption. Of all the samples tested, 63/110(57.3%) samples from religious places, 28/56(50%) from hospitals, 25/50(50%) from bus stands/railway stations, 84/190(44.4%) from schools, 32/100(32%) from BSF checkposts, 5/19(26.5%) from hotels and 3/25(12%) from ice factories were found to be unsatisfactory. Out of the 570 unsatisfactory samples detected, 72% samples from submersible pumps,50% from hand pumps, 45.4% from taps,29.2% from tube wells and 28.5% from domestic tap supply were found to be contaminated. On Eijkman test 20/25(80%) of the suspicious samples turned out to be unsatisfactory. So, availability of safe drinking water still remains a much sought after commodity for majority of public in developing countries like India.
Source of support: Govt. of Punjab (India)
Water, the elixir of life is getting polluted due to rapidly increasing population, urbanization, construction of new buildings and deforestation. Water pollution is becoming a global problem threatening human existence .Water contamination occurs from human, animal and industrial wastes mixing into it. They contain a variety of bacterial, viral, protozoan pathogens and helminth parasites along with chemical pollutants. Consumption of such unsafe drinking water may expose a high proportion of the community to the risk of outbreaks of intestinal and other infectious diseases (1) .In fact, more people would die of consuming unsafe drinking water and unsanitary conditions by the year 2020 than from AIDS, if steps to improve water quality are not taken on war footing
Ideally, drinking water should not contain any micro organisms which are known to be pathogenic. It should be free from bacteria indicative of faecal pollution. The primary bacterial indicator recommended for this purpose is the coliform group of organisms
In themselves, coliforms are not dangerous but their presence indicates that the fecal matter has entered the water supply, and fecal bacteria have not been removed or killed by the purification processes. Therefore the water supply is liable to contamination with dangerous intestinal pathogens
So, in the interest of public health water supplies (piped/unpiped) and samples from distribution sources must be checked from time to time to ensure that safe quality drinking water is supplied to the public
The present study was conducted with the objective of assessing the bacteriological quality of water in different drinking water sources in Amritsar District (India).
Materials And Methods
A total of 1200 drinking water samples from taps of piped supply (550), hand pumps (380),submersible pumps (125 ),tube well(120) and ice factories (25)from various places in Amritsar district received during the period of Jan 2007 to Dec,2008 were analyzed in Microbiology Department of Govt. Medical College, Amritsar.
The samples were received in sterilized, standard, specified glass bottles of 230 cc capacity along with properly filled prescribed proforma. The samples were received, stored (in case of delay) and processed in accordance with the guidelines described in standard methods
Differential coliform count (Eijkman’sTest) was performed on suspicious water samples. Subcultures from positive presumptive test were made into MacConkey broth and peptone water and incubated at 44OC in thermostatically controlled water bath for overnight. Presence of Esch.coli was confirmed by the production of gas from lactose at 44O C and indole from tryptophan.
The results obtained are tabulated as follows
After subjecting the samples to Eijkman test, 20 samples turned out to be unsatisfactory while 5 were satisfactory.
* Indicates number of results after Eijkman test
In current study, out of 1200 samples tested, 570(47.5%) were found to be unsatisfactory for human consumption. The percentage of samples tested by other workers has been as high as 81.3%
Another important observation in our study was that the coliform growth up to satisfactory levels was found only in 200 samples (33.3%). Out of the 25 suspicious samples tested, which could harbor other coliforms also, 5 samples (20%) turned out to be satisfactory which means no faecal contamination of the source with Esch.coli.
Shockingly 63/110(57.3%) samples from religious places, 28/56(50%) from hospitals, 25/50(50%) from bus stands and railway stations, 84/190(44.4%) from schools,32/100(32%) from BSF check posts, 5/19(26.5%) from hotels and 3/25(12.0%) from ice factories were found to be unsatisfactory. This is of grave concern as they may cause acute health hazard in the form of water borne diseases to the local as well as travelling population (Amritsar is a holy city)
Another startling finding in the study was that 250/550(45.5%) of the water samples supplied through municipal taps(presumed to be pre-treated) were also found to be unsatisfactory, whereas other workers have reported 20% of the treated water supply to be contaminated (
Thus, it is concluded from the present study that the alarmingly high percentage of unsatisfactory water samples from submersible pumps, taps and from places visited by common people like religious places, bus stands, railway stations, hospitals and schools calls for public awareness and an immediate attention by the authorities as well. Piped water supply from the source to the consumer has to be regularly monitored by the authorities to ensure the delivery of pure and germfree water.