SOURCES OF WATER 5 



driven and dug wells and cisterns all being extensively used, al- 

 though the water from lakes and streams is generally used only 

 for stock. Each of these sources under some conditions may yield 

 entirely safe and satisfactory supplies, while under other con- 

 ditions certain of them may be a constant menace to the health. 

 Of the various sources mentioned the ground water is on the 

 whole the most satisfactory for farm use, because it is least liable 

 to pollution, and streams and ponds are the most unsatisfactory, 

 because of the ease and frequency with which they are contami- 

 nated. Fortunately, however, the latter are very seldom used for 

 drinking and domestic purposes, being utilized mainly for stock, 

 on which the effect of moderate pollution is not apparent. The 

 underground supplies, whether from wells or springs, although safe 

 in many localities, are far from being universally so, the safety de- 

 pending mainly on their location and on the nature of their pro- 

 tection. These are discussed in the following sections. 



