Paragraph 9: Boron 



Boron is found in the natural ground and sur- 

 face waters in some areas of the United States, 

 notably in the Western States where as much as 

 5 to 1 5 mg/1 are encountered. However, extensive 

 data on boron in both well and surface waters in 

 North America show that the amount of boron 

 normally encountered is less than 1 mg/1. The 

 ingestion of large amounts of boron can affect the 

 central nervous system and protracted ingestion 

 may result in a clinical syndrome known as 

 borism. 



Boron is an essential element to plant growth 

 but is toxic to many plants at levels as low as 

 1 mg/1. The Public Health Service has established 

 a limit of 1 mg/1 which provides a good factor of 

 safety physiologically and also considers the do- 

 mestic use of water for home gardening. 



Paragraph 10: Dissolved Oxygen 



Criteria for dissolved oxygen are included, not 

 because the substance is of appreciable significance 

 in water treatment or in finished water, but because 

 of its use as an indicator of pollution by organic 

 wastes. It is intended for application to freeflowing 

 streams and not to lakes or reservoirs in which 

 supplies may be taken from below the thermocline. 



Paragraph 11: Fluoride 



The Subcommittee recognizes the potential 

 beneficial effects of fluoride ion in domestic water 

 supplies but recommends no "desirable" concen- 

 tration since any value less than that recommended 

 for the permissible limit would be acceptable from 

 the point of view of a water pollution control pro- 

 gram. Rapid fluctuations in raw-water fluoride ion 

 levels would create objectionable onerating prob- 

 lems for communities supplementing raw-water 

 fluoride concentrations. The permissible criterion 

 is the upper limit of the recommended range in 

 Drinking Water Standards (10). 



Annual average of Maximum daily air 

 temperatures ^ F: Limit mg/l 



50.0 to 53.7 1.7 



53.8 to 58.3 1.5 



58.4 to 63.8 1.3 



63.9 to 70.6 1.2 



70.7 to 79.2 1.0 



79.3 to 90.5 0.8 



^ Based on temperature data obtained for a minimum 

 of 5 years. 



Paragraph 12: Hardness 



A singular criterion for the maximum hardness 

 in public water supply is not possible. Hardness in 

 water is largely the result of geological formations 

 with which the water comes in contact. Public ac- 

 ceptance of hardness varies from community to 

 community. Consumer sensitivity to objectionable 



hardness is related to the hardness with which he 

 has become accustomed. Consumer acceptance of 

 hardness may also be tempered by economic 

 necessity. 



Hardness should not be present in concentra- 

 tions that will cause excessive soap consumption, 

 or which will cause objectionable scale in heating 

 vessels and pipes. In addition, varying water hard- 

 ness is objectionable to both domestic and indus- 

 trial water consumers. With varying hardness, the 

 soap required for laundry, the effect on manu- 

 factured products, and the damage to process 

 equipment (such as boilers and cooling coils) can- 

 not be anticipated and compensated without facili- 

 ties which are not available to most water users. A 

 water hardness criterion must relate to the hard- 

 ness which is normal to the supply and exclude 

 hardness additions which will cause variations. 



A criterion for objectionable hardness must be 

 tailored to fit the requirements of each community. 

 Hardness more than 300-500 mg/1 as CaCOs is 

 excessive for public water supply. Many consum- 

 ers will object to water harder than 150 mg/1. In 

 other communities, the criterion for maximum wa- 

 ter hardness is considerably less than 150 mg/1. A 

 moderately hard water is sometimes defined as 

 having hardness between 60 to 120 mg/1. 



Paragraph 13: Nitrate plus Nitrite 



A limit of 10 mg/l(N) of nitrate ion plus nitrite 

 ion will be recommended by Drinking Water 

 Standards (10). Because the nitrite ion is the 

 substance actually responsible for causing methe- 

 moglobinemia, a combined limit on the two ions 

 is more significant than a limit on nitrates only. 



Paragraph 14: pH 



Most unpolluted waters have pH values within 

 the range recommended as a permissible criterion. 

 Any pH value within this range is acceptable for 

 public water supply. The further selection of a 

 specific pH value within this range as a desirable 

 criterion cannot be made. 



Paragraph 15: Phosphorus 



The Subcommittee has considered establishing 

 criteria on phosphorus concentrations but has not 

 been able to establish any generally acceptable 

 limit because of the complexity of the problem. 

 The purpose of such a limit would be twofold: 



(a) To avoid problems associated with algae 

 and other aquatic plants, and 



(b) To avoid coagulation problems due par- 

 ticularly to complex phosphates. 



Phosphorus is an essential element for aquatic 

 life as well as for all forms of life and has been 

 considered the most readily controllable nutrient in 

 efforts to limit the development of objectionable 

 plant growths. Evidence indicates that high phos- 



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