Shima drinking water--a bacteriological analysis

300 water samples, 60 from piped supply and 240 from 20 natural sources were analyzed bacteriologically for four important bacterial indicators every month over a period of one year. The MPN of total coliforms, Escherichia coli, Streptococcus faecalis were detected by multiple tube method and Clostridium perfringens was isolated using litmus milk medium. From piped water supply, only one sample was found unfit for human consumption. The plate count at 37 degrees C and 22 degrees C varied from 0.5 x 10(3) to 15 x 10(3) per ml. of water. From natural sources, MPN indices for coliforms, Esch. coli and S. faecalis varied from 3 to > 1800, 0 to > 1800 and 0 to 540 per 100 ml. of water respectively. About 1/3rd of samples showed presence of Cl. perfringens. The plate count varied from 1.0 x 10(3) to > 150 x 10(3) per ml. of water. Salmonella typhi was isolated in 1.25% samples by membrane filtration technique. The water from all the natural sources was unfit for human consumption whereas piped water supply was of good quality in general.