الفهرس 
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Abstract
Surface water, ground water and sea water may all be considered as the general source of public water supply.
It is essential that the supply of water for human uses should be free from unpleasant or harmful impurities. This water is never found in nature. Surface water commonly contains suspended impurities such as silt, organic matter from vegetable or animal origin and dissolved minerals from the soil with which the water has come into contact. For this reason, it is subjected to different sources of pollution which affect its physical, chemical or biological characteristics and subsequently render it harmful to public health. Water may require treatment for a number of reasons. The most important is the necessity of removing the harmful germs that cause disease. For potability, it must be free from unpleasant tastes and odours and must have an inviting appearance.