According to the CDC, "Drinking water sources are subject to contamination and require appropriate treatment to remove disease-causing agents." Most Americans use chemically treated tap water. And like most individuals who pay attention to your health, you might be wondering "how is my tap water made?" Or "where does my tap come from?" Fortunately, the Center for Disease Control and Prevention has made available the process by which nearly all tap water systems adhere to. So, let's go ahead and dive into the steps that involved with bringing tap water to you and your family.
Step 1: Coagulation and Flocculation
During this process, positively charged chemical agents are added to the water source. The positively charged chemicals eventually bind with the negatively charged material, which coagulates and forms "floc." An easier way of understanding this process is by envisioning, sand, being suspended in cloudy water. In this scenario, the murkiness of the water is made up of the suspended sand. And when a chemical agent is added, the sand settles to the bottom of the container which renders the water more clear.
Step 2: Sedimentation
During sedimentation, the floc that was created during coagulation settles to the bottom of the containment vessel. The water can then be passed on to the next stage of filtration, and the "floc" can be disposed of as waste.
Step 3: Filtration
Finally, we arrive at filtration. During this stage, the free-flowing water from Stage 2 will then pass through a variety of filtration media (e.g. sand, charcoal, and gravel). The varying quality and size of each material will stop prevent bacteria, dissolved solids, parasites, and chemicals from passing on to the next stage.
Step 4: Disinfection
During this stage, a disinfectant is added to the water in order to kill any germs that may be present. The disinfectants used are most often chlorine and chloramine. State agencies are responsible for determining the allowable concentrations that simultaneously kill bacteria, but also keep the water potable.
Step 5: Fluoridation
Municipal systems add fluoride to tap water in order to improve dental health. Although the importance of fluoride is widely debated, the practice remains in effect for most of the United States.