Buildings and Yards. 517 



them, the disagreeable effect of those waters on the skin, and the deposits 

 formed by precipitation in cooking or in the laundry. Other things being 

 equal, therefore, a soft water not affected by lime or magnesia is to be pre- 

 ferred. Unfortunately, there are other things which cause pollution 

 of a worse sort, — things which, in general, are of an animal nature. 

 Such pollution usually will be associated with human habitations and 

 are the results, in one form or another, of human life. Surface waters, 

 such as brooks or ponds, are most likely to be contaminated in this way, 

 and, fortunately, the contamination can usually be recognized by even 

 the most casual observation. If the brook flows through bottom lands, 

 where cattle are pastured or where cultivated lands are manured, or 

 if the brook receives the drainage from houses and barns, the quality 

 of the water inevitably suffers. Mere contamination by animal wastes, 

 however repulsive aesthetically, is probably not in itself dangerous^ 

 but if the drainage comes from diseased men or animals, the water may 

 become a carrier of the disease and so cause severe epidemics. On' this 

 account, it is altogether wisest to avoid surface water which may at any 

 time be exposed to animal or human contamination. It is not easy to 

 pronounce on the probable pollution of wells, and they are therefore the 

 most dangerous sources of water supply. If deep, they may furnish 

 water which is merely hard. If shallow, drainage from privies or barn- 

 yards may make them certain sources of disease or death. Nor is it 

 possible to pronounce by inspection of the surroundings only, on the 

 probable purity of the water. If they are dug through a bed of clay 

 with all chance for water to wash in over the top avoided, they are prob- 

 ably good. But if they are entirely in gravel, not far from a privy or 

 drain, the water would be very suspicious. It is further to be noted that 

 exemption from a serious disease for a period of years does not mean 

 that a certain well water is pure, because the specific cause of a disease 

 may not have been in the water; but if the conditions are such that a 

 disease may be passed on fron\,a privy through the water supply back to 

 the household, sooner or later it will be done. 



3. Methods and cost of installation 



The simplest and best method of supplying a house with water, is to 

 pipe the water from a spring or brook at a point high enough to cause 

 the water to flow freely from the house faucets. If from a spring the 

 quantity must be examined. This can be done by measuring, in pailfuls, the 

 overflow of the spring. Not counting the water needed for the barn, it has 

 been shown that a flow at the rate of 600 gallons in twenty-four hours is 

 needed for a family of ten, — a flow at the rate of about two quarts per 

 minute, or five minutes to fill a ten-quart pail. If this is just the rate of 

 flow of the spring, there is enough water, but it may be thought that the 



