148 DOMESTIC WATER SUPPLIES FOR THE FARM 



settling, the action of frost, penetration of tree roots, etc. If there 

 is any likelihood of the cistern filling to the top, an overflow pipe 

 may be provided to advantage. 



The use of wood-curbed cisterns, mentioned on p. 143, should 

 be discouraged. Such cisterns not only commonly taste strongly 

 of the wood, but they permit the entrance of both pollution and 

 mineralized ground waters through their cracks, and are other- 

 wise unsatisfactory in many ways. Care should also be taken 

 with the equipment used for conducting the water to the reser- 

 voir. There should be adequate roof-gutters and leader pipes of 

 galvanized iron or other non-rusting material to carry the water 

 to the ground, while tiled pipes with cemented joints should be 

 used to conduct the water through the ground from the house to 

 the cistern. It is always desirable to provide a "leader cut-off," 

 or "separator," which consists of a metal deflector not very 

 unlike the common dampers in stovepipes which works within 

 the leader. By means of this deflector the first more or less dirty 

 wash from the roof is turned aside and carried out through an 

 opening in the leader pipe, and it is only when the deflector - 

 which is operated from the outside is turned that the water 

 passes into the cistern. There are also automatic appliances for 

 accomplishing the same purpose. 



Cistern Filters. In addition to the deflectors, cut-offs, or 

 other devices for separating the first more or less contaminated 

 run-off from roofs, further attempts at purification are occasion- 

 ally made by passing the roof-waters through filters before finally 

 conducting them into the cisterns. 



Sand and animal charcoal are the most effective of the various 

 filtering materials commonly available to the farmer, and both 

 are highly efficient filtrants when properly cared for. Unfortu- 

 nately, however, unless frequently renewed (at least in part), 

 they rapidly become contaminated both by the materials strained 

 from the water and by the growth of bacteria, which develop with 

 great rapidity within the filtering material as its pores become 

 clogged. Water passing through a filter under these conditions 



