fection before use for domestic purposes, washing 

 or hydrocooling of agricultural products, or in 

 milkhouse operations. 



Surface water is subject to wide fluctuations in 

 temperature and mineral content as well as bac- 

 terial flora. Passing through decaying vegetative 

 matter, it may pick up colors and odors which, 

 though they may not be a deterrent to proper sani- 

 tation, may make the water objectionable for 

 drinking and other domestic uses. 



Ground water is that which exists in a saturated 

 zone of the earth's crust. Most of this supply 

 originates as atmospheric water. Sewage and other 

 types of liquid waste usually have relatively little 

 effect on ground water quality in deep formations. 

 Surface water may be important to ground water 

 levels in the area of rainfall but may be deposited 

 far from the point of extraction. 



The principal ground supplies are springs or 

 wells. Quality may differ greatly between deep and 

 shallow wells. Water from relatively deep wells is 

 usually of acceptable bacteriological quality and 

 can be used for drinking without treatment, al- 

 though it frequently has high mineral concentra- 

 tions. Shallow well water is seldom this pure. 

 While bacteria and colloidal materials are com- 

 monly removed as water seeps through the ground, 

 mineral substances are frequently dissolved to 

 create waters with varying degrees of hardness. 

 Occasionally, objectionable gases such as hydro- 

 gen sulfide may be dissolved which produce un- 

 desirable odors or tastes. More commonly, carbon 

 dioxide is dissolved, creating acid water with an 

 enhanced ability to dissolve minerals. 



Shallow wells may yield appreciable numbers of 

 many types of bacteria and, less commonly, 

 yeasts. It has been reported that infectious hepa- 

 titis and typhoid fever are problems arising from 

 contaminated shallow wells in some areas {77). 

 This pollution may be caused by seepage of con- 

 taminated surface waters. Fragmented or cavern- 

 ous rock formations may contain crevices which 

 extend to the surface, particularly in limestone 

 areas. Shallow wells may decrease in quantity (or 

 dry up completely) under drought conditions. 

 Wells and springs should be properly disinfected 

 usually by chlorination after construction and after 

 any repair or alteration to the system. 



In some locations, sand and gravel strata exist 

 below a stable water table. These strata may pro- 

 vide a dependable source of water similar in qual- 

 ity to that of shallow wells in the area. These sys- 

 tems are commonly located near a lake or stream; 

 however, an adequate distance should separate the 

 source from the system to allow for suitable filtra- 



tion. The area above the infiltration system also 

 must be protected to prevent pollution by animals 

 or sewage (104). 



Other Considerations Regarding Sources of 

 Water: Farm water supplies which are obtained 

 from municipal systems usually are free from 

 pathogenic bacteria and objectionable odors, 

 colors, or tastes. The primary problem with such 

 sources, in addition to cost considerations, is re- 

 lated to the control of nonpathogenic micro- 

 organisms and minerals occurring in the supply. 



Many farm operations utilize water from sev- 

 eral sources during the year. Assuming the relative 

 quality of supplies as noted above, such combina- 

 tions of sources may cause problems in dairy sani- 

 tation. Sanitation chemicals are selected to soften 

 hard water and provide sufficient reserve to remove 

 dairy films. Several sources which are intercon- 

 nected in one system and then utilized as needed 

 during the year, may have entirely different hard- 

 ness and pH relationships, greatly affecting the 

 strength of cleaning solutions. Incomplete sanita- 

 tion for even a short period can cause film develop- 

 ment (milk and/or water) which will have a long- 

 term effect on raw milk quality unless removed by 

 supplemental treatment. 



Objectionable Natural Constituents of Water: 



The objectionable foreign materials commonly 

 present in water can be divided into several groups. 

 These are : 



( 1 ) Suspended matter. This includes clay, silt, 

 and sand. The first two are found chiefly 

 in untreated surface supplies while sand is 

 commonly associated with well supplies. 



(2) Materials causing taste, odor, and color. 

 These impurities normally occur as the 

 result of one or more of the following: 

 dissolved organic matter, dissolved organic 

 gases, hydrogen sulfide, earthy constitu- 

 ents, algae, phenols, or other wastes. Hy- 

 drogen sulfide is more commonly asso- 

 ciated with ground supplies, while the other 

 impurities occur more often in surface 

 waters. 



(3) Materials causing hardness. As water 

 moves on or through the earth, it may col- 

 lect salts of calcium and magnesium, and 

 to a lesser extent other minerals. While 

 many of these salts are of little concern in 

 drinking water, they can affect seriously 

 water to be used in cleaning and cooling. 



Bicarbonates, sulfates, and chlorides are the 



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