Repository: UIHistories Project: SWE - Proceedings of the First International Conference of Women Engineers and Scientists [PAGE 145]

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it becomes a part of the ground water or water systems, rain water may contain large quantities of mineral substance or atmospheric gases dissolved in it. Ground water and surface water which do not contain any particular pollutants are to be considered as pure water. It is therefore more practical to talk about the usability of water for the purpose concerned than about the purity of water. Water can be divided into the following categories according to use: household water, which includes drinking water; water for industrial use; farming water; swimming water; and fishing water. Each category has particular specifications as regards quality, The following quality specifications apply to household water: 1. 2. It may not contain anything which causes disease. It may not contain toxic or factors otherwise dangerous to human beings. As regards taste, odor, color, brightness, hardness and temperature, household water has to meet moderate requirements »

3.

The standards stipulated for drinking water vary slightly from country to country; for instance, Finland has not as yet any official standards. As the best recommendation for the quality of drinking water, there can be proposed the standard of the World Health Organization (WHO) given in the Table 1, which lists the substances that cause hazards to health if they occur in large concentrations. It is not possible to give common quality specifications for industrial water, as the requirements for the quality differ, dependent on the field of production and the methods employed. The quality specifications for household water are mostly valid for the water to be used in raising livestock, although it may be pointed out that the qualifications are not as strict for drinking water for cattle and for irrigation water as those for drinking water. The hygienic point of view is most important in evaluation of the quality of swimming water. The bacteorological quality, waste waters and epidemic conditions must be taken into consideration in determining whether water is suitable for swimming. Fishing water may not contain toxic substances, such as copper salts, cyanides and free chlorine, in such amounts that they exercise a poisonous effect on fish. The oxygen content of the water must be sufficiently high to ensure that the stock of fish can thrive there. In the search for elucidation of the reasons for the mass death of fish which have occurred in some waters, it has most frequently been found that the supply of oxygen is inadequate; the fish have simply suffocated because of lack of oxygen.

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