THE HOME WATER SUPPLY 



49 



Brooks. It may sometimes happen that a house is so 

 situated that water from a brook may be piped to the house. 

 But generally such sources of water are undesirable. They 

 are open to many sources of contamination and during the 

 summer they are apt to dry up altogether. 



Cisterns. Cisterns are sometimes used as a source of 

 drinking water. If proper precautions are taken, these may 

 be fairly satisfactory. The cistern should be water-tight 

 to prevent impurities from entering. Various kinds of 

 impurities gather on the roof, and therefore arrangements 

 should be made so that the first washings from the roof 

 during a rain may be conducted away, and then the later 

 washings turned into the cistern. 



Pumps. After the purity of the water is assured, the next 

 question to consider is the method by which the water is 

 brought into the house and distributed. 

 One of the most common methods, espe- 

 cially for cisterns, is the pump. The 

 ordinary cistern or suction pump consists 

 of a cylinder C, with a piston P that works 

 inside the cylinder. This piston has a 

 leather washer so that it fits the cylinder 

 tightly. In the center of the piston is a 

 weight or valve V so arranged that pres- 

 sure from above closes it tight, while 

 pressure from below opens it. At the top 

 of the pipe T, where the pump is fastened, 

 is a similar valve 5 which opens up and 

 lets the water through, but which closes 

 down and prevents the water from going 

 back. A pipe T connects the cylinder 

 with the well or cistern. 



How the pump works. In order to understand how the 

 pump works, let us suppose that the cylinder is full of water 

 and that the pump handle is down. When the handle is 



FIG. 15. A suction 

 pump. 



