What is the first step in treating water to make it potable?

The first step in treating water to make it potable is coagulation. During the coagulation process, chemicals are added to the water that cause small particles, such as dirt and bacteria, to clump together into larger particles, called floc. This process is essential because it prepares the water for subsequent treatments by making it easier to remove impurities.

Coagulation often involves the addition of coagulants like aluminum sulfate, which help in binding the suspended particles. Once the floc forms, it can be removed from the water through sedimentation or filtration. This step is crucial as it significantly reduces the amount of contaminants in the water prior to more advanced purification methods, ensuring that the overall water treatment process is efficient and effective.

While chlorination is a disinfection method used later in the process to kill remaining pathogens, filtration involves the physical separation of the floc from the water, and aeration is typically used for reducing dissolved gases, these processes are not the initial step in making water safe for drinking.