The present study was carried out to evaluate the quality of different sources of drinking water from various parts of Guwahati city
To draw out information on drinking water sources, methods of purification and on the perception of drinking water as a source of illness a study was carried out in the Microbiology Department of Gauhati Medical College and Hospital. A total of 254 water samples were collected from Greater Guwahati and for the purpose of the study; the city was divided into four distinctive zone namely-North, South, East and West Guwahati. The study also lays emphasis on the quality of ground water and supply water.
The water samples were analyzed from different parts of Guwahati city from the period 1/6/05 to 31/5/06. Samples were evaluated by MPN using MacConkey broth. Fecal Escherichia count was done by Eijkman test1.
In the 254 water samples evaluated, the overall average Coliform count irrespective of season in the two Urban supply systems, well, tube well and deep tube well are 6.3, 9.8, 46.1, 30,3.8 respectively. The overall count was highest in the well water followed by tube well, supply water and deep tube well.
Season had a significant effect on the variation of Coliform count in the ground water. The overall average bacterial count irrespective of sources during pre-monsoon, monsoon, post-monsoon and winter is 90, 160, 50, 10 respectively. Statistical analysis revealed significant difference in the average bacterial count of water from different sources.
The grading of samples on the basis of Coliform count revealed that the percentage of excellent, satisfactory, suspicious and unsatisfactory water samples were 7.69%, 44.41%, 76.47%, 11.76%, from Urban supply, 0, 0, 30.35%, 69.65% from well, 0, 18.18%, 9.1%, 72.73% from tube well, 52.63%, 31.58%,15.79%, 0% from deep tube well, 0, 0, 0, 100% from stream, 100%,0,0,0 from bottled water/filter water. The percentage of water sample with no Coliform bacteria was 100%, 52.63%, 7.69%,0% in the bottle water/filter, deep tube well, urban supply and other sources of ground water supply respectively.
Out of 254 different water samples examined 221(87%) were positive for Coliform bacteria. Out of which 151(59.44%) were Escherichia coli, 57(22.44%) were Klebsiella, 13(5.12%) were Citrobacter and 34(13.38%) of the samples were Coliform free.
Results from supply and ground water were outside the acceptable limit recommended by WHO for drinking water. Of all sources Deep tube well water showed the least average MPN. So it can be concluded that both ground water and supply water should be properly treated if used for drinking purpose.
Coliform Count, Eijkman Test
