TREATMENT OF FARM SEWAGE. 
8 9 
It is very easy for the farm to make use of the principles of a septic 
tank in caring for and even utilizing its sewage. Fig. 19 shows 
diagrammatically a means of accomplishing it efficiently and at 
comparatively small expense. The diluted sewage from the house 
is conducted to a tank sunk in the ground at any convenient distance. 
The tank should be of such a size that it will hold the entire sewage 
for twenty-four hours. If each person uses twenty gallons of water 
frvfefek etc. 
Mtrates (/nscM) 
FIG. 20. The nitrogen cycle. 
per day, the tank for a household of ten should be three feet deep, 
two feet wide and six feet long. It must be covered so as to exclude 
air and light, and the sewage must flow slowly and quietly through 
the tank, thus making it a septic tank. The discharge from the 
tank is best received into a second tank from which it can be 
conducted to a stream or upon the garden for fertilizing and 
irrigating it. 
