that Committee has been described in the section 

 on Public Water Supplies (par. 21). These recom- 

 mendations are shown in table IV— 5. 



TABLE IV-5. Recommended Limits for 



Chlorinated Organic Pesticides in 



Farmstead Waters 



TABLE IV-6. Allowable Concentrations of 

 Trace Ions in Farmstead Waters 



Turbidity 



The presence of suspended material such as 

 clay, silt, finely divided organic material, and 

 plankton contributes to the cloudiness or turbidity 

 of water. Turbidity in excess of 5 units (159) is 

 easily detectable in a glass of water and is usually 

 objectionable for aesthetic reasons. Clay or other 

 suspended particles may not adversely affect 

 health, but water containing such particles may 

 require treatment to make it suitable for certain 

 uses. Following a rainfall, variations in the ground 

 water turbidity may be considered an indication 

 of surface pollution. 



Trace Elements 



Attention has been given only to those trace ele- 

 ments which commonly occur in water supplies 

 or those which are regarded as being particularly 

 hazardous. The development of standards for 

 every potentially hazardous substance which may 

 occur in a water supply is an impossible task. The 

 user of farmstead water supplies should ascertain, 

 however, that there are no geological or environ- 

 mental conditions which render the supply unsafe 

 due to the presence of substances not covered 

 herein. 



Table IV-6 lists the allowable concentrations of 

 trace ions which, if exceeded, would make a water 

 supply unsatisfactory for farmstead use. 



The concentration of the trace substances sum- 

 marized in table IV-7 should not be exceeded if 

 other sources of water are available. Water to be 

 used in milkhouse sanitation should not contain 

 more than 0.1 mg/1 of iron or copper. 



Water containing more than 2.5 mg/1 fluoride 

 is detrimental during tooth formation and should 

 not be used without suitable treatment (12, 191). 



TABLE IV-7. Recommended Limits for Certain 

 Trace Substances in Farmstead Waters 



Radionuclides 



All radiation exposure is regarded as harmful 

 and any unnecessary exposure to ionizing radia- 

 tion should be avoided. The acceptability of a 

 farmstead water supply containing radioactive 

 materials should be based upon the determination 

 that the intake of radioactive substances from such 

 water when added to that from all other sources is 

 not likely to result in exposure greater than that 

 recommended by the Federal Radiation Council 

 (56). Supplies containing radium-226 and stron- 

 tium-90 are acceptable without consideration of 

 other sources of radioactivity if the concentrations 

 of these radionuclides do not exceed 3 and 10 

 pc/1, respectively. In the known absence of 

 strontium-90 and alpha-emitting radionuclides, 

 the water supply is considered acceptable if the 

 gross beta activity does not exceed 1,000 pc/1. 

 If the gross betta activity is in excess of this 

 amount, a more complete radiochemical analysis 

 is required to determine that the sources of radia- 

 tion exposure are within the limits of the radiation 

 protection guides. 



Pathogenic and Nonpathogenic Microorganisms 



The presence of any coliform organisms in a 

 water supply suggests fecal contamination. The 

 common technique used to measure coliform or- 

 ganisms, however, is based on a probability form- 

 ula and compliance with the criterion is met if 

 the sample is found to contain no more than one 

 coliform organism per 100 ml of water. If routine 

 chlorination or other effective means of disinfec- 

 tion is used, levels up to 100 coliform organisms 



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