272 



MICROBIOLOGY OF WATER AND SEWAGE 



subsoil " B " to the drainage. Water falling on the surface of the ground 

 would penetrate through the soil to the upper portion of the subsoil, and 

 then move along it in the direction of the greatest slope. In this sketch, 

 the subsoil drainage is away from the well; and in this respect the well is 

 located properly; but, in respect to the surface drainage, improperly 

 located. A better place for the well would be at the letter "X ". 



In Fig. 114 the surface drainage — including that from the adja- 

 cent outhouse at 3, which is too close to the well — is toward the barn, 

 and away from the well; but the subsoil drainage from all the buildings, 



-Soil 



Fig. 116.— Construction of a model well. On the right is brick construction, on 

 the left stone construction, as illustrated. (Original.) 



except the house, is in the direction of the well; and thus contamination 

 of the water supply is liable to occur. 



Fig. 114 shows a well properly located as regards both surface and 

 subsoil drainage. Such a well will supply pure water, if it is properly 

 constructed. 



Fig. IIS shows the proper construction of a well with brick or stone. 

 Large vitrified drain pipes with cemented joints will answer equally well 

 when there is an abuijidant supply of water; but in case, the supply of, 



