96 Bacteria in Relation to Country Life 



and carefully kept, it makes, also, a good and healthful 

 drinking-water. 



Cistern-water is collected by allowing the rain that 

 falls on the roof to run into receptacles made of wood, 

 stone, concrete, or metal. This method of collection 

 exposes the water to more or less contamination, for, 

 apart from the dust particles and bacteria in the air, 

 carried down by the falling rain, the roof itself supplies 

 varying quantities of dust, droppings of birds, insects, 

 and other objectionable materials. Small animals, 

 birds, and insects may also find their way to the cistern 

 itself, thus adding still further to the amount of con- 

 tamination. When we remember that the particles of 

 dust borne by the winds may contain disease germs 

 still capable of development, for example, those of ty- 

 phoid, tuberculosis, and diphtheria, we realize at once 

 that cistern-water may become a carrier of disease. 



To make matters worse, the cisterns are frequently 

 located in the ground near sources of pollution, and are 

 not always impervious to infiltration from adjacent soil. 

 Cisterns made of wood, brick, or stone, may thus be- 

 come polluted' from nearby cess-pools and privy-vaults. 

 This is not a mere assumption, but a fact repeatedly 

 demonstrated by actual examination. Cases of typhoid, 

 sometimes several in one family, have been traced to 

 the use of cistern-water. Numerous instances of other 

 intestinal disturbances are also on record. A large pro- 

 portion of the cisterns examined have been found to 

 contain the colon bacillus and, likewise, considerable 

 nunibers of other bacteria. This condition is not at all 

 surprising in view of the very infrequent cleaning of 



