2 BULLETIN 57, U. S. DEPARTMENT OF AGRICULTURE. 
tion with the' Minnesota State Board of Health, indicate that of 79 
carefully selected and typical water supplies in 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 investigated were polluted. During these investiga- 
tions 23 of the farms examined showed a record of typhoid fever. 
F\ T. Shutt. 1 of the Canada Experimental Farms at Ottawa, re- 
viewing his study of the subject since 1887, states that of the farm 
water supplies examined 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. Eain 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 washing 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 supplies 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, partial 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. " 
1 Reprint from Pub. Health Jour., State Med. and Sanit. Rev., 1912, April. 
