It must not being contaminated with bacillus or heavy metal. If we drink water that contaminated with bacillus or heavy metal, according to the level of accumulation, human body could get fatal damage instantly or after a while. So we should not drink contaminated water. Human beings intake water indirectly by food as well. So the foods that human beings eat everyday should take attentive care. There must be sufficient amount of minerals dissolved with well balance. Kobayasi, semi emeritus professor of faculty of agriculture of Okayama university Japan, found that people in a place, where the drinking water contains high level of calcium, have less people suffering cerebrovascular disorder than people in a place where the drinking water contains low level of calcium. Kimura emeritus professor of Wakayama state medical college researched unusual disease in the Wakayama region, symptom of the disease was that the activity of brain and spinal cord gets slower and muscle cannot work. As a result of the research, it was because of the water, which contains low level of calcium. Even though we don't take this particular example, we can find it from an example that we don't drink distilled water as a drinking water. Foods from the ground do not contain much of mineral if the ground having acidity. So they taste bad. It must be weak alkaline Because our body fluid is weak alkaline, it is good to drink weak alkaline water that suits our body. (Harvard medical university) In order to prevent our body from acidification, we should take a lot of fruits and vegetables that are alkaline. Few cities in U.S. deliver tap water that already made to weak alkaline. It must have plentiful of hydrogen ion. Human bodies absorb oxygen from the air, but could not excreting remaining active oxygen inside of the bodies. Water has plentiful of hydrogen ion, eliminates active oxygen from our bodies. It is called 'antioxidant'-eliminating active oxygen; active oxygen is the reason of aging and disease. If we keep far away the aging and disease by eliminating active oxygen, there is no better way than that for youth and health. Water particles must be small. It is faster to be absorbed if particles of water are small.