common anions in farm water supplies, while cal- 

 cium, magnesium, and sodium are the most fre- 

 quently encountered cations. The bicarbonates 

 produce a condition known as temporary hardness. 

 This is the major cause of hardness problems in 

 farmstead water supplies, but precipitation is 

 rapid if bicarbonates are present. A hardness film 

 also forms when equipment is rinsed with hard 

 water. Upon evaporation of the water, hardness 

 minerals remain as a film on equipment. 



Hardness is objectionable for most domestic 

 uses and causes problems in dairy sanitation since 

 precipitation of hardness chemicals (waterstone) 

 will trap milk residues. These then harbor and 

 provide nutrients for microorganisms which, in 

 turn, affect both the keeping quality and the sani- 

 tary quality of the raw milk supply as measured 

 by usual regulatory procedures. "Stone" buildups 

 on milk-handling equipment can only be removed 

 by special cleaning procedures. 



(4) Iron, copper, and manganese. These ele- 

 ments are troublesome in the water supply 

 of dairy farms. They can be deposited on 

 milk contact surfaces during normal sani- 

 tation procedures, then be removed by 

 milk due to its slightly acid nature. When 

 iron and copper are present in milk in 

 concentrations as low as 0.1 mg/1, they 

 will contribute to the development of 

 oxidized (cardboardy) flavors {72). 

 These minerals may exist in the water 

 supply itself or result from corrosion of 

 the water pipes. Acid waters (pH<7.0) 

 are particularly troublesome in causing 

 corrosion and subsequent copper or iron 

 contamination in the water. 



Iron and manganese may be found in some well 

 water supplies. When present, they cause a par- 

 ticularly objectionable red-brown stain which is 

 difficult to remove from surfaces being cleaned 

 without special techniques. 



Nonpathogenic Bacterial Contaminants: Micro- 

 organisms are commonly present in surface waters 

 and waters held in reservoirs. Coliform bacteria in 

 a water supply have been accepted as presumptive 

 evidence that contamination with pathogenic spe- 

 cies is likely since isolation of every potential type 

 of pathogen is not practical at this time. Likewise, 

 the dairy industry has been concerned with the 

 coliforms since they are commonly used as an 

 indication of contamination with fecal pollutants 

 in the vicinity of the sampling location. 



Many other nonpathogenic species of micro- 



organisms are found in farm water supplies. Al- 

 though most of these are harmless, certain of them 

 contribute to the development of colors, odors, 

 tastes, and turbidity. Algae, diatoms, and protozoa 

 produce odors in the water but these are seldom 

 factors in milkhouse sanitation. One group of orga- 

 nisms known as "iron bacteria" actually feed on 

 iron pipes. These slimy, mucoid cells may multiply 

 in the presence of iron, produce undesirable flavors 

 and clog pipes or seriously depress flow rates 

 {200). Ropy milk is a classical example of a 

 fault which may be due to contaminated water. 



There is considerable recent evidence that one 

 group of water organisms, commonly referred to 

 as psychrophilic (cold loving) organisms, may 

 have a considerable effect on the keeping quality 

 of raw milk. The pychrophiles include many 

 species capable of breaking down the fat and 

 proteins in milk to produce serious physical and 

 chemical changes in the product (165). 



Research has shown farm water supplies to be 

 of variable but generally poor quality. While the 

 majority of water samples would be acceptable by 

 presumptive coliform determinations, tests could 

 indicate the supplies contained other organisms 

 capable of affecting milk quality (79). 



Studies have shown that coliform bacteria and 

 most other bacteria are easily destroyed, even 

 when water is quite turbid. While treated waters 

 may satisfy standards for potable supplies, certain 

 psychrophilic bacteria and other spoilage orga- 

 nisms may survive chlorine treatment and con- 

 tinue to be a factor in milk quality control (6, 7, 

 77, 79, 82, 186). Laboratory studies indicate that 

 some of these putrefactive bacteria will survive 

 even 10 mg/1 residual chlorine (6, 7, 79, 81). 

 Results with iodine treatments were similar {6, 7, 

 79). The literature shows that certain psychro- 

 philic organisms are quite resistant to all sanitizing 

 agents {81). Sublethal doses of chlorine may effect 

 a temporary decrease in the growth of surviving 

 organisms but the rate of increase after this tem- 

 porary lag may be greater than that of the control 

 sample {32). Many of these organisms grow at 

 low levels of organic matter. They are actively 

 proteolytic, lipolytic, or putrefactive. They grow 

 well at temperatures barely above freezing and 

 may have serious consequences in present milk 

 handling methods where lengthy storage of raw 

 milk is common. As modern milk handling meth- 

 ods make it likely that at least small amounts of 

 water will enter the milk, it is evident that farm 

 water supplies must be free of these microorga- 

 nisms. 



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