The Bridgeport evening farmer., 1913-06-12

frAcGCa1 M6CfbOOS Of Handling
 Public Water Supplies.
 A simple, direct description of methods of purifying water for drinking is given in a report by George A. Johnson, just publish ed by the United States GeoIogi- cal Survey. The report describes the various types of water supp ply systems used by cities in the United States, sets forth the principal advantages and disad- vantages of each, and gives brief history of the development of waterwOrks systems and the effect of their installation on the health of communities.
 The necessity for purifying water for use in cities is clearly shown, not the least important value of water purification being the insurance it provides against disease. Mir. Johnson shows by very reasonable estimates that the use of pure water annually saves from the ravages of wa terborne typhoid fever alone more than four times the cost of purifying the water. The substitution of pure for impure water supplies in the United States would save annually some 26,OOO lives and fully $2OO, ,OOO,- GOO.
 The paper includes a histori- cal sketch of modes or systems of water purif1cation, from the storage works and cIarificat1on by alum used by the ancient Chinese to. the present-day methods of filtration, coagula- ton and sterilization. Prepara- tory treatment, in which the wa ter is passed through sed1men- tation tanks, coaguIafion ba- sins, or roughing filters to re- move a portion of its color or turbidfty, 1s discussed in detail.
 In slow sand filtration water is passed slowly through great beds of fine sand, on which it leaves it's impurities. TIustra- tdons of several successful slow sand filtration plants are given and special features of constr1lc- tion, sand-handItng, sand-vash- ing, and operation are explained and discussed. The costs of con Struction and of maintenance GhAA0 OkGS1G6A4O4 d1LO EA1OStG 1Ak AN0@ tail for 8 number of plants of this type. The report also de- scribes and illustrates i'm a siIn- liar manner rapid sand filters, which differ from slow sand hI- ters chiefly in being constructed in smaller units and of cOarser sand, in always having coaguIa- tion as a preliminary treatment, fva .Aca<7- eaHH as fast, and in being cleaned by sending a reverse current of wa ter through the filters.
 The softening of municipal wa ter supplies in connection with their pUrifcation is discussed and the advantages and IiInita- tiOns as well as tho details of this treatment are set forth In instructive detail. Hard waters produce scale in and shorten the life of boilers, causing waste of coal. They are i'll suited to the needs of many water using in- dustries and cause an enormous waste of soap in Iaundries and in ordinary domestic operations. In many instances the saving or soap is alone sufficient to nay the costs of softenfng.
 In this report technical terms have been avoided so far as pos sible and the subject-matter is presented so clearly and concise ly that it can be readily under stood by the non-tec1lnicaI read er.. It contains much infornaa- ton of value to city officials, boards of health, and others fn- terested in sanitary engineering as applied to waterworIzs plan ming, construction, maintenance. and operation. It is published as Water-Supp1y Paper S15 and copy can be obtained free of charge on application to the Df- rector, United States Geological Survey, Washington, D. o.