THE WATER SUPPLY IN DRY AREAS 447 



tion is light, and, second, that the roof surface is rela- 

 tively small. A building, say, 40 by 60 feet should 

 catch approximately 14,080 gallons of water in one year 

 from a rainfall of 15 inches, providing none of it is 

 allowed to waste. This may, in some instances at 

 least, furnish water to meet the needs of the household 

 and of a small garden as well. 



The water caught in draws and ravines may be of 

 considerable volume. Its source is water that comes 

 from winter rains, from the melting of winter snows, 

 and from rains in summer when the water falls so 

 rapidly as to run away, in part at least, over the surface. 

 To hold this water may not always be easy, because of 

 the length and height of the dam required, and in some 

 instances because of seepage through the soil. Water 

 from roofs is caught and held in cement lined cisterns. 

 Cement may also be used in arresting flood waters,, but 

 when thus used the cost entailed may be very consid- 

 erable. 



In all parts of the dry areas, water obtained from 

 springs may be utilized to great advantage. The regret- 

 ful fact is that springs, although so precious, are so 

 scarce in dry areas. Notwithstanding, they may be used 

 with much profit even though distant from the home. 



Instances are on record wherein a tiny, insignificant 

 spring has been made to supply the home, although lo- 

 cated several miles away, the water being carried 

 through pipes. 



Water from streams is equally valuable when it is 

 easily accessible, but in very many instances what may 

 be termed living streams are very few and far between 

 in dry areas. Unless sufficiently near to be fed by melt- 

 ing snows on the mountains, these streams are much 

 liable to become dry and remain so soon after the season 

 of greatest precipitation until the arrival of the season 

 of precipitation that follows. In a few instances, the 



