CHAPTER XVII 



WATER SUPPLY 



Source of supply. There are two sources from which a 

 supply of water may be obtained for farm use : surface water, 

 collected in lakes, ponds, or streams; and ground water, 

 found in certain strata of the soil, in caverns, in beds, or in 

 fractures of the earth's shell. 



Surface waters are very open to pollution and for this 

 reason are not generally used for consumption in the home, 

 although when conveniently located they may prove quite 

 suitable for the farm animals. Springs may be of deep origin 

 or almost entirely surface water. They are subject to pol- 

 lution at a distance or from immediate washing into the 

 spring bed and are not to be considered safe, pure waters 

 simply because they appear as springs. Local protection 

 of a spring is comparatively simple, but it is a difficult mat- 

 ter either to locate or to prevent pollution at a distance. Of 

 the ground waters the most desirable are those found in sand 

 or gravel strata, for they have passed through many feet 

 of natural filter. Ground waters are usually accessible 

 only through the medium of wells, with or without pumps 

 to extract the water. 



Wells. Shallow. The dug or shallow well is usually 

 limited to 30 or 40 feet in depth and 3 to 6 feet in diameter. 

 It may be curbed from the solid rock, with rock, brick, con- 

 crete, or timber. If timber is used, it is desirable that the 

 lagging be placed vertically for the top 8 feet. The decay 

 of the lagging is most rapid where there is an opportunity 

 for drying out of the wood, to be followed by subsequent 

 wetting and drying. If these members are placed vertically, 

 they may be removed, piece by piece, and replaced without 

 difficulty. 



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