what is water?
Water is a substance composed of the elements Hydrogen and Oxygen and it exists abundantly on the Earth as a gas, a liquid and a solid. Everbody knows the formula is H2O. As a gas we call it steam, as a liquid we call it water and as a solid it is called ice. Although the molecules of water are simple in structure, the physical and chemical properties of water are extremely complicated and no attempt is made to explain them here.
Water is a colourless, tasteless and odourless liquid at normal temperatures. One of its most important properties is its ability to dissolve many other substances. The versatility of water as a solvent is essential to all living organisms which use aqueous solutions such as blood and digestive juices for carrying out the biological processes absolutely essential for life.
Without water, life would not exist. As the water available for drinking purposes gets less and less and the quality deteriorates, so the demand for potable water will escalate. This will especially be the case in developing countries without access to the high level and expensive technology needed to convert man-polluted water into a state suitable for drinking, cooking and living.
About 97% of all the water on Earth is found in the salty oceans which cover about 70% of the Earth’s surface. [ Reference 1]. Only 3% of the water on Earth is “fresh water” and much of this is locked up in the polar icecaps or in deep underground aquifers. Much of the remaining available river and sub-surface water is too polluted to drink safely. This pollution arises not only from man-made industrial, agricultural and domestic waste water but is also naturally occurring, where water deep underground stored for millennia in rock strata has over long periods of time dissolved minerals from the surrounding rocks.
Health problems produced by excess arsenic and fluoride salts in the drinking water supply can occur and this is particularly in the Indian sub-continent where Aid agencies drilled deep tubewells to avoid the germs in dirty surface water and assumed, without testing, that all deep water was chemically clean. It took many years for the accumulated minerals to produce their dreadful effects and many more years for the authorities to realize and accept the problem, which has still not been overcome
