The Latin expression “aqua pura, aqua vitae” can be translated as “pure water, living water,” or “pure water is the water of life.” Water is the mater (mother) and matrix (container, structure, or medium) of life.
No water, no life; life cannot exist without water. Today water in its raw state is not suitable for drinking, as it contains numerous contaminants that are known to be dangerous to human health and all living things. If it is too acidic, it can also be harmful to inorganic materials like soil and stone.
While scientific advances have created many of our problems with water, scientific advances are now working to solve them. New devices are being invented to heal aqua ailments, which in turn will safeguard our health and the health of our crops and animals and even the soil itself. Wonderful devices are available to purify tap water and make it taste like nectar. Ordinary tap water can be made suitable for drinking.
Pure water is essential to healthy living. Ordinary tap water, even though treated by the supplier, contains numerous contaminants, including bacteria, algae, fungi, viruses, minerals, and chemicals. A water purifier will remove these organisms and contaminants to make the water fit to drink. Water purifiers save us from potential bacterial and viral diseases that can easily spread through contaminated water.
Water Purification Techniques
Different types of water purifiers use different techniques. Common techniques include boiling, distilling, carbon filtering, reverse osmosis, ion exchange, electrode ionization, water conditioning, and plumbo-solvency reduction.
Carbon filters are commonly used in home water systems. Charcoal, a form of carbon, absorbs many contaminants due to its high surface area and mode of preparation. As the water passes through the activated charcoal, contaminants are removed by one of two carbon filtering systems: granular charcoal filtering or submicron solid-block carbon filtering.
Granular charcoal is not as effective as submicron carbon filtering for removing contaminants such as mercury, asbestos, volatile organic chemicals, pesticides, disinfection by-products (the trihalomethanes), MTBEs, PCBs, and similar substances. The submicron solid-block carbon filter removes all contaminants.
Home water filters for drinking water sometimes contain silver. Small amounts of silver ions released into the water have a bactericidal effect.
In reverse osmosis, mechanical pressure is applied to a contaminated solution to force it through a fine, semipermeable membrane that will only allow water molecules to pass through, thus trapping the contaminants on one side and ensuring clean water on the other. It is said to be the most thorough method of large-scale water purification.
Ion exchange is another technique used in water purification. Most common ion exchange systems involve a zeolite resin bed. Unwanted Ca2+ and Mg2+ ions are simply replaced with soap-friendly Na+ or K+ ions. A more stringent type of ion exchange exchanges H+ ions for unwanted cations and hydroxide (OH-) ions for unwanted anions. The result is H+ + OH- + H2O. This system is recharged with hydrochloric acid and sodium hydroxide, respectively, resulting in deionized water.
Electrodeionization involves passing the water through a positive electrode and a negative electrode. Ion-selective membranes make the positive ions separate from the water and move toward the negative electrode and make the negative ions move toward the positive electrode. This technique results in deionized water of a high purity. Before electrodeionization, the water is usually passed through a reverse osmosis unit to remove organic contaminants and debris.
Hard water conditioning reduces the effects of minerals dissolved in water. Hardness salts become deposited in water systems subject to heating because of the decomposition of bicarbonate ions, which creates carbonate ions that crystallize out of saturated solutions of calcium or magnesium carbonate. Water with high amounts of hardness salts can be treated with soda ash (sodium carbonate) to precipitate out the excess salts through the common ion effect. The precipitated calcium carbonate is of a very high purity and is traditionally sold to toothpaste manufacturers.
Plumbo-solvency reduction is used in areas with naturally acidic waters of low conductivity, such as surface rainfall in mountains of igneous rocks, that are capable of dissolving the lead in lead pipes. Small quantities of phosphate ions are added and the pH is slightly increased. This greatly reduces plumbo-solvency by coating the inner surfaces of the pipes with insoluble lead salts.