An Investigation into the Clogging of the Filter Beds at Topchanchi Waterworks during Hot Weather

were noticed all along in these samples. It is unusual to find the presence of stable iron compounds in the surface waters of a lake. Twenty samples of water drawn from the second valve were analysed and showed signs of growth, as well as decay, of low forms of vegetable life and the presence of iron sufficient to choke the filter beds and to foster the growth of Crenothrix, one of the clogging agents. The temperature of the water plays an important part, 70??80?F. being congenial to the growth of low forms of vegetable life, whereas the temperature of the surface water, which is over 85?F., helps the vegetable decay. The growth