promptly as possible (within 24 hours) after collection
or were stored at 40C in a refrigerator until use. A multiple
tube fermentation technique or Most Probable Number
(MPN) technique [7] was used to determine bacterial
indicators as Total Coliforms (TC), Faecal Coliforms (FC)
and Faecal Streptococci (FS) according to standard methods
as described in APHA [7]. Multiple tube fermentation
method used in present work included measurement of
total plate count and MPN of coliform. After incubation for
24 hours at 350C results were recorded when acid and gas
liberated in durham tubes with change of colour to yellow.
Lactose broth was used as a medium for the growth of
coliform. Number of positive test tubes with acid (yellow
colouration) and gas production were matched with the
McCardy’s Statistical Table and the most probable number
(MPN) of coliforms present in 100ml of each sample was
thus determined. Different pathogenic bacteria were
enumerated by serial dilution method. 0.1 ml aliquots of
each dilution (10-1 to 10-7) directly from tubes was inoculated
in triplicate on FC agar, Mac Conkey agar and FS agar by
spread-plate method for enumeration of Faecal coliform, E.
coli and Faecal streptococci respectively. The culture plates
were incubated at 37oC for 24h. The removal efficiency of
bacterial indicators was calculated using the following
formula