The need for a safe source of pure water has always been an issue. It has become even more of a cause for concern with the recent development of many synthetic chemicals that present a difficulty in water purification.
Drinking water treatment has taken various forms throughout history. The earliest and perhaps most widely used until the past several decades is the process of distilling water. This age-old method consists of heating water to its boiling point, causing the water molecules to transform into a gaseous state, recognized as steam. The steam condenses and is collected by various methods.
This technique of separating water molecules from possible contaminants is effective in some applications. However, it requires a lot of effort to obtain the results needed for mass collection of water. Additionally, there are many harmful elements that have a lower boiling point than water; consequently, they will become condensed along with the water molecules and will be collected as well.
Reverse osmosis was developed as a drinking water treatment method recently. This method is based on the scientific properties of water molecule movement. In its natural state, water will separate its molecules from some impurities based on mass and density. The application of this principle to a system of water treatment relies on the osmotic motion of water molecules and screening of any contaminants.
A semi-permeable membrane is used in a reverse osmosis system. This membrane is a grid of very fine pores that allow for the passage of water molecules through the membrane, while those elements that are larger in molecular size will be trapped by the membrane. The separated water molecules are then moved through the membrane to a storage unit by means of pressure, thus completing the reverse osmosis process.
While this method is more effective in removing a greater number of harmful elements than is distillation, it is still considered to be impractical in the sense that 3 gallons of water are lost in the creation of one gallon of purified water.
Additionally, many potentially harmful elements are of an even smaller molecular size than is water, such as MTBE and THM elements that have been found to be carcinogenic. The loss of trace minerals, such as potassium and calcium, due to their molecular size is also a negative aspect in the reverse osmosis process.
By far, the most cost-effective and efficient means of purifying water is the use of carbon filters. This is the only method approved by the EPA, and is especially effective as a water treatment method when incorporated into a multi-media system of filters and screens.