SEPTIC SORE THROAT 161 



with sewage containing the ^organism. The methods of dis- 

 posal of both municipal and farm sewage often are such 

 as to permit of its introduction into the water. Munici- 

 palities often draw their water supplies from a body of 

 water that is contaminated by sewage. In individual sup- 

 plies, the farm well is often located in close proximity to 

 the outhouse, and if the well is not protected from the 



S POOL 



GROUND WATER* 



GROUND WATER' 



y?li\y*. 



' 



Pig. :i7. Typhoid Fever Spread by Water 



The entrance of infectious material into a cesspool is likely to contaminate the 

 well unless it is some distance from the cesspool 



entrance of surface water, or seepage from the upper soil 

 layers, infectious material may be carried into the well by 

 the drainage water. If the well is a drilled one, the iron 

 casing should extend to an impervious layer of soil or rock, 

 and the curb should be constructed so that no waste water 

 can find its way into the well. If the well is dug instead of 

 drilled, the upper portion of the protecting wall should be 

 laid in concrete, and the surface properly protected by a 

 concrete curb. 



No definite statements can be made as to the distance in- 

 fectious material may be carried by the drainage water, as 

 this depends much on the porosity of the soil. If the soil is 

 clay, gravel, or sand, the movement of infectious matter will 

 be for only a short distance ; but if the soil is underlaid with 

 limestone, underground channels may develop by the solu- 



