2.2. Treatment of drinking water
To protect erosion of filter’s top layer during filtration of water, a layer of flat stone was raised above the sand.Water was added to the filter tank continuously for several hours. The filter media was kept away from drying by fitting the outlet pipe in such away that the height of the out-let tap was 5 cm above the top layer of the filter sand bed. The filtration rate was controlled between 0.2 l/h and 1.2 l/h and the filtration rates for the units having a treatment time of 2, 4, 6, 8, 10 and 12 h were