Why Improtence Water?

Water is the common name applied to the liquid form (state) of the hydrogen and oxygen compound H2O. Pure water is an odorless, tasteless, clear liquid. Water is one of nature's most important gifts to mankind. Essential to life, a person's survival depends on drinking water. Water is one of the most essential elements to good health -- it is necessary for the digestion and absorbtion of food; helps maintain proper muscle tone; supplies oxygen and nutrients to the cells; rids the body of wastes; and serves as a natural air conditioning system. Health officials emphasize the importance of drinking at least eight glasses of clean water each and every day to maintain good health.

Properties: The freezing point of water is 0° C (32° F), and its boiling point is 100° C (212° F). Water reaches its maximum density at 4° C (39° F) and expands upon freezing. Water combines with salts to form hydrates and reacts with metal oxides to form acids (see Acids and Bases).

Occurrence: Water is the only substance that occurs at ordinary temperatures in all three states of matter: solid, liquid, and gas. As a solid, ice, it forms glaciers, frozen lakes and rivers, snow, hail, and frost. It is liquid as rain and dew, and it covers three-quarters of the earth's surface in swamps, lakes, rivers, and oceans. Water also occurs in the soil and beneath the earth's surface as a vast groundwater reservoir. As gas, or water vapor, it occurs as fog, steam, and clouds.

Water in Life: Water makes up 50 to 90 percent of the weight of living things. Protoplasm is a solution of water and fats, carbohydrates, proteins, and salts. Water transports, combines, and chemically breaks down these substances. Water also aids the metabolic breakdown of proteins and carbohydrates.

Natural Water Cycle: The continuous movement of water between the earth and the atmosphere is the hydrological cycle. Water vapor from water and land surfaces and from living cells circulates through the atmosphere and falls as rain or snow. When it reaches the earth, water either flows into streams and then into oceans or lakes, or it enters, or infiltrates the soil. Some water becomes soil moisture, which may evaporate directly or move up through the roots of plants and be released by leaves. Some water percolates downward, accumulating in the so-called zone of saturation to form the groundwater reservoir, the upper surface of which is the water table. Under natural conditions, the water table rises in response to inflowing water and then declines as water drains into natural outlets such as wells and springs.

Composition: Because water dissolves numerous substances in large amounts, pure water rarely occurs in nature. Precipitation absorbs carbon dioxide and other gases, as well as traces of organic and inorganic material from the atmosphere. Because water reacts with minerals in the soil and rocks, surface and groundwater may contain many different dissolved substances. Surface waters may also contain domestic sewage and industrial wastes. Groundwater from shallow wells may contain nitrogen compounds and chlorides, but water from deep wells generally contains only dissolved minerals. Seawater contains many soluble compounds in addition to salt.