THE PURITY OF DRINKING-WATERS. 131 



the location of a well and its depth. In very deep wells bacteria 

 have a chance to be filtered out of the water as it passes through the 

 soil before it reaches the well, so that, if care be taken to prevent 

 contamination at the surface, the water is safe. This is always true 

 of artesian wells. But in the shallow well the chance of dangerous 

 contamination is great. The most common, as well as the most 

 dangerous contamination of well-water, comes from the privy vault. 

 Both vault and well are, for convenience, placed near the house and 

 frequently near each other. The well is sunken several feet below 

 the surface of the ground, while the vault is close to the suiface. 

 The contents of the vault inevitably soak into the ground and will be 

 surely distributed in every direction, taking naturally the course of 

 water currents under the surface. It is almost certain that, if the 

 well is close at hand, the water courses will lead to it and the con- 

 tents of the vault will thus find their way into the well. It requires 

 no argument to demonstrate the danger from such conditions. Nor 

 will anyone familiar with agricultural communities fail to recognize 

 that exactly such conditions frequently exist. Indeed, they are 

 sometimes even worse than this, for one may find the vault actually 

 upon an elevated mound and the well sunk into the soil at its foot 

 not twenty feet away. 



Under such conditions one need not be surprised at the spread of 

 typhoid. A single case of the disease on the farm will contaminate 

 the vault, and may soon infect the well. The infection may be 

 from water percolating through the soil or from surface currents in 

 time of rains, washing the contaminated water into the mouth of the 

 well. The farmer rinses his milk pails in the water from the well 

 and subsequently puts his warm milk in the cans. The typhoid 

 bacilli which were in the well thus get into the milk, where they 

 find conditions for rapid growth, and the farmer, wholly unconscious 

 of having done anything out of the way, distributes the bacilli to the 

 neighboring community which he supplies with milk. A typhoid 

 fever epidemic breaks out which remains a mystery, unless some one 

 is sharp enough to trace it to its source in the farmer's well. 



Such is not an imaginary instance, but represents a type of 

 typhoid epidemic many times repeated. It is simply illustrative of 



