Less than 1 of every 5,000 litres of water on earth can be found as either surface or atmospheric fresh water. However, this minute fraction still represents an estimated total volume of more than 200,000 cubic kilometres, enough to cover all of Canada to a depth of 17 metres. As we noted earlier, water readily dissolves most salts. However, water is a poor solvent for proteins and other large organic molecules in living cells. This means that liquid water can transport nutrient elements to and within living cells without dissolving and destroying the organic molecules of which cells are made.
Water also transports waste elements away from cells.
This water penetrates the cell protoplasm, but does not dissolve it. Without water, there would be no life. This means that the distribution of life on earth is highly dependent on the distribution of water. Our needs, both metabolically and otherwise, are often affected by the distribution of water and by competition for available water. Of course, water is not evenly distributed , and this has a major impact on us, both as living organisms and as a complex social species.