posted by y912f on .
#33. In two or three well-developed paragraphs, explain how water is treated so that it can be used for safe drinking water. Include definitions of the terms potable and pathogens.
There are many steps to how water is treated so that it can be potable, or used for safe drinking water. Water treatment removes harmful elements from the water, such as pathogens, which are organisms that cause illness or disease. The first step is Filtration, this is the first filtration step. In this step, the source water supply is filtered to remove large organisms and trash. In the second step, coagulation, Alum is rapidly mixed into the water and forms sticky globs called flocs. Then, bacteria and other impurities cling to the flocs, which settle to the bottom of the tank. The third step is the second filtration step. In this, the layers of sand, gravel, and hard coal filter the remaining impurities. Chlorination is the fourth step of water treatment. During this step chlorine is added to prevent bacteria from growing in the water. In the fifth step, aeration, air is forced through the water to release unwanted gases. This reduces odor and improves taste. The last step of the water treatment process is additional treatment. In some communities, fluoride may be added to prevent tooth decay. Sodium compounds or lime may also be added to soften hard water. Finally, the treated water is then pumped from storage tanks to homes and businesses.