A manual of hygiene and sanitation . rainfall gives gallons per square yard of area onwhich it falls, equivalent to 22,617 gallons per 60 square feet of collecting surface per head,and estimating the loss by evaporation, etc., at 20 per cent.,an annual rainfall of 30 inches would give only about 2gallons per head per day, or just about sufficient for cook-ing and drinking purposes and none for the other needsof the household. Rain-water may be collected from roofs or from a plot 150 WATER. of ground paved for the purpose with slate or cement, andbe led by proper conduits to
A manual of hygiene and sanitation . rainfall gives gallons per square yard of area onwhich it falls, equivalent to 22,617 gallons per 60 square feet of collecting surface per head,and estimating the loss by evaporation, etc., at 20 per cent.,an annual rainfall of 30 inches would give only about 2gallons per head per day, or just about sufficient for cook-ing and drinking purposes and none for the other needsof the household. Rain-water may be collected from roofs or from a plot 150 WATER. of ground paved for the purpose with slate or cement, andbe led by proper conduits to a cistern. It should be filtered(Fig. 25) before passing into the cistern, while the cisternitself should be such as to give no unpleasant taste or in-jurious substance to the water, should be so situated thatit will receive no rubbish or impurities and that the watermay be kept cool, and should be cleaned regularly andsufficiently often to keep the water sweet and wholesome. Fig. 25. Movable covering stone. Paving. Level of Cistern A simple filter for rain-water. (Notter and Firth.) ^ As rain-water contains considerable carbon dioxide andother gases, its solvent powers are increased, and cisternsshould not be lined with lead, copper, zinc, or iron, lestthese metals be taken up by the water and produce harm-ful results. These remarks do not apply to the so-calledrustless iron now much used; but galvanized iron should Fig. 25 illustrates a filter for an underground cistern. One of similarconstruction can be readily made for cisterns above ground, the latterbeing always preferable. RAIN-WATER. 151 not be used, as it may give up zinc to the water. Cementshould also be used in lining brick or stone cisterns insteadof mortar, as the latter may add lime to the water andrender it hard. Underground cisterns for storing rain-water should beavoided where J30ssible, since they are liable to soil-air orsewage contamination unless absolutely air- and water-tight. Nor should the ove
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Keywords: ., bookcentury1900, bookdecade1900, booksubjecthygiene, bookyear1903
