WATER SUPPLY, PLUMBING, ETC., FOE COUNTRY HOMES. 33 



the soil pipe, and connections should he tightly made. The sewer 

 inside the cellar wall should always be soil pipe; tile should never be 

 used except outside of the wall. A soil-pipe trap should be provided 

 at the house foundation, as shown in figure 26. Every fixture should 

 have a trap to prevent foul air from coming back through the waste 

 pipe. Vent pipes should be provided on all waste pipes to prevent 

 siphonage and the consequent destroying of the traps. Figure 27 

 (p. 34) shows a good arrangement of sewer plumbing.^ Note the 

 traps and vent pipes on each waste pipe. The least sizes of waste 

 and vent pipes are given in the table below. 



Sizes of waste and vent fifes. 



Xarae of pipe. 



Diameter. 



Name of pipe. 



Diameter. 



Main and branch soil pipe 



Inches. 

 4 



2 

 li-2 



14 

 3-i-4 



Wash tubs, 14-inch waste pipe to 2- 



Indies. 





11-2 



Branch waste pipes for kitchen sinlts. . 

 Bath or sink waste pipe 



Waste pipe for 3 or 4 tubs 



' 2 



Main vents and long branches 



2 



Basin waste pipe 



Branch vents for traps over 2 inches. . . 

 Branch vents for traps less than 2 inches 



2 





li 





^ 







All plumbing should be tested by filling with water or smoke to 

 detect leaks. 



SEWAGE PURIFICATION AND DISPOSAL. 



The problem of the purification and disposal of farm sewage by 

 small private systems differs somewhat from that of city sewage dis- 

 posal, owing principally lO the extreme fluctuations in flow, small 

 size of the system, fresh character, and variation in the quality of 

 the sewage. 



The process of sewage disposal is parth^ mechanical and partly 

 bacterial, consisting of (1) preliminary or tank treatment and of (2) 

 final treatment, which is application to a natural soil by surface or 

 subsurface distribution or to a specially prepared filter. 



PRELIMINARY OR SEPTIC-TANK TREATMENT. 



The exact nature of the action which takes place in a septic tank is 

 a subject of dispute among sanitary experts and bacteriologists. 

 Several theories have been advanced, but it is apparent that no 

 definite conclusion has been reached. Some authorities advocate 

 the use of open ventilated tanks, others advocate the use of air-tight 

 tanks. 



Experience has shown that, in a small sewage disposal system, a 

 dark, air-tight tank of sufficient capacity and so constructed that 

 sewage may remain in it entirely at rest for a period of from 1 8 to 24 



1 Univ. Mo. Engin. Expt. Sta. Bui. 3. 



