2 BULLETIN 57, U. S. DEPARTMENT OF AGRICULTUEE. 



tiou with the Minnesota State Board of Health, indicate that of 79 

 carefully selected and typical water suppUes m Minnesota 20 were 

 good and 59 were polluted. Of the polluted wells 11 were so located 

 that even extreme care would not make them safe; 10 were poorly 

 located, but improvements in the protection from surface wash and 

 infiltration would make them safe; 25 were bad only because of poor 

 surface protection and could easily be made safe. Practically all the 

 surface supplies mvestigated were polluted. During these mvestiga- 

 tions 23 of the farms examined showed a record of typhoid fever. 



F. T. Shutt / of the Canada Experimental Farms at Ottawa, re- 

 viewing his study of the subject since 1887, states that of the farm 

 water supplies examuied 30 per cent may be classified as safe and 

 wholesome, 25 per cent as suspicious and probably, contaminated, 

 36 per cent as seriously polluted, and 9 per cent as nonpotable through 

 high salinity. 



SURFACE SUPPLIES. 



CONTAMINATION. 



Surface water supplies are those most liable to pollution, and 

 authorities agree that they are the most unsatisfactory for farm use. 

 Streams and ponds receive the greater part of the surface wash from 

 the immediate neighborhood, and in many cases barnyard or stockyard 

 drainage from points remote from where the water is taken for house- 

 hold use. Streams or ponds located in pastures, manured fields, or 

 where stock can gain access to them are polluted. Sometimes sewage 

 and house drainage are emptied into streams and ponds. In fact, 

 since they are open and unprotected, there are a thousand and one 

 different sources of pollution for such supplies. Rain waters from 

 the roof are polluted by dust, dirt, and leaves, which collect in the 

 eaves trough, and by the droppings from birds. 



Surface water supplies should therefore not be used for household 

 purposes, not even for washmg milk cans or for laundry purposes, 

 unless no other supply is available. And it may be safely assumed 

 that the person who drinks water from surface suppUes endangers his 

 health if such supplies are not first protected from the sources of 

 contamination as far as possible and then purified. 



CISTERNS. 



In localities where underground waters are hard to obtain, cisterns 

 may be used for the filtration, pa/'tial purification, and storage of rain 

 water, and surface supplies. The size of the cistern will depend on 

 the number of persons in the house and on the general water consump- 

 tion, as discussed hereafter, under "Pumping, storage, and distribu- 

 tion." 



I Reprint from Pub. Health Jour., State Med. and Sanit. Rev., 1912, April. 



