482 WATER SUPPLY AND SEWAGE DISPOSAL 



Such surface water will necessarily carry with it much un- 

 decayed or but partially decayed vegetable and animal matter. 

 Such matter later decays (Art. 470, Chap. VIII) rendering the 

 water unwholesome for use and not infrequently causing sick- 

 ness and sometimes death. The danger is greatest when the 

 waste matter is from the human body. This is so because 

 the waste matter thrown off from the human body is very 

 likely to contain microorganisms which cause human diseases. 

 Typhoid fever is often caused by drinking water containing 

 typhoid bacilli (Art. 511). 



564. Protecting a Shallow Well against Surface Water. 

 All shallow wells should be protected against surface water. 

 Some protection is provided by constructing the walls and 

 cover of the well water-tight. When the walls and cover of a 

 shallow well are water-tight, there is no opportunity for the 

 contaminated surface water to get into the well until it has 

 percolated through the soil to the bottom of the well. In 

 passing thus through the soil, the water is fairly well filtered, 

 and the danger of contamination is lessened. 



III. CITY WATER SYSTEMS 



565. Privately Owned and City Owned Water Systems. 

 In communities where the families live in homes separated by 

 considerable distances, each family must provide its own water 

 supply. But as soon as a region becomes thickly settled, it 

 becomes somewhat less expensive and in every way better for 

 the whole community to be served by a common water system. 

 City governments generally maintain such water systems to 

 supply all who live within the city limits. Sometimes a pri- 

 vate corporation is granted a FRANCHISE by the terms of which 

 the corporation may lay pipes in the public streets and may 

 sell the water to customers under certain conditions and regu- 

 lations stated in the franchise. In a similar manner, private 

 corporations very frequently are granted franchises to fur- 

 nish customers with electric current and gas for lighting, cook- 



