FARM SANITATION 



505 



Fig. 308 is a general view of a septic tank which has been 

 built for as little as $18.65. It has a plank top, and the only 

 means of cleaning it out would be to uncover the earth and 

 remove the planks. Fig. 

 309 is a more expensive 

 plant, with a filter bed 

 attached. The filter bed 

 complete will cost by it- 

 self about $20. The best 

 results can be secured 

 with a tank provided with 

 a siphon. Fig. 310 shows 

 a plan for laying the tile 

 system to filter the discharge from the septic tank. 



It is remarkable how thoroughly sewage can be purified by 

 an efficient plant. Often the effluent or final discharge from 

 the filter bed will compare in purity with the best well water. 



Fig. 310. A plan of a tile system foi 

 filtering the discharge from a septic 

 tank. 



QUESTIONS 



1. How is sewage purified that is discharged into a river? 



2. What are the objections to a cesspool as a means of disposing 

 of sewage? 



3. Discuss the construction of the cesspool. 



4. How is sewage purified in a septic tank? 



5. How can complete purification of the sewage be obtained? 



6. Why is it best to have the sewage applied intermittently to the 

 filter bed or irrigation tile? 



7. Discuss the construction of the septic tank. 



8. Estimate the cost of a sewage disposal plant for a household of 

 ten people. 



