WATER SUPPLY, PLUMBING, ETC., FOE COUNTRY HOMES. 3 



The cistern should be of water-tight construction, to prevent leak- 

 age and to prevent pollution from the neighboring soil. It should 

 have an overflow drain and a tight cover. There should also be suit- 

 able provision for straining or filtering the water previous to its en- 

 trance to the cistern. 



The cistern should ordinarily be in two compartments, with a filter 

 wall of porous brick between. One compartment serves then as a 

 settling chamber and the water receives a final filtration before enter- 

 ing the storage compartment. 



Concrete is probably the most sanitary and durable material for 

 cisterns. In general, the walls and floor should be 6 or 8 inches thick 

 and well reenforced and the concrete should be carefully proportioned 



INLET 



3-0" 'a- 



Fig. 1. — Reenforced concrete cistern, showing arrangement of forms and reenforcing. 



and mixed. A mixture of 1 part cement to 2 or 2^ parts of clean 

 sharp sand and 4 or 5 parts of clean and fairly small crushed rock or 

 gravel is satisfactory for fairly water-tight concrete. The inside sur- 

 face should be coated with a 1 to 2 cement mortar. Figure 1 shows a 

 circular cistern of average size sufficient for a family of 6 or 8 people. 

 In constructing such a cistern, make a circular excavation 16 inches 

 wider than the desired diameter of the cistern and about 16 inches 

 deeper than the desired depth. Make a cylindrical form as shown in 

 the figure, the outside diameter of which will be the inside diameter 

 of the cistern. Mix the concrete in small batches fairly wet and 

 tamp in between the form and the earth. To construct the conical 

 portion, build a floor across the top of the cylindrical form, leaving a 

 hole of the desired size in the center. Brace the floor well with up- 

 rights from the cistern bottom. Build a cone-shaped mold of wet 



