78 DOMESTIC WATER SUPPLIES FOR THE FARM 



from hen yards, from hogpens and from the manure piles near 

 barns, eventually enters the ground and finds its way in one form 

 or another to the ground water below. Drainage from manured 

 fields and from pastures occupied by stock may also be a promi- 

 nent source of pollution. Much of the polluted water from such 

 sources is purified by passage through the ground and the danger 

 of pollution of well waters by seepage is commonly exaggerated, 

 yet gross carelessness in locations of wells near privies, cesspools, 

 drain-pipes and other filth receptacles is prevalent in many farm 

 districts. 



One of the greatest sources of pollution for farm wells is 

 the entrance of material at the top, and dug wells are especially 

 liable to contamination of this sort, though other well types are 

 not entirely exempt (Fig. 34). 



Of the material entering a well from the open top dust is an 

 important source of contamination. It is always present in the 

 air and the amount actually settling is very many times more than 

 the conspicuous dust coatings collecting in buildings. In fact, in 

 open wells, especially in regions where brisk winds are common, 

 the accumulations sometimes amount to several inches in a year. 

 Many wells which are cleaned only once in two years are found to 

 contain as much as 6 inches of foul-smelling black muck, repre- 

 senting the dust and other refuse entering the well in that length 

 of time. 



Small animals, such as toads, mice, moles and snakes, fall into 

 the well in times of drought when the sources of water they 

 usually depend on have failed. 



Except that it keeps the larger animals out and is a con- 

 venience in using the well, the ordinary plank covering affords 

 but little improvement over the open well. Crevices almost in- 

 variably exist through which the smaller animals may find access, 

 and the dirt washed through the cracks by the pump drippings 

 may be almost equal to that entering through an open top. 

 Moreover, it is a very dangerous type of dirt, as in many places it 

 includes filth from domestic fowls and from the shoes of farm 



