Which of the following is NOT commonly used as a source drinking water?

Salt water is not commonly used as a source of drinking water because it contains high levels of dissolved salts, such as sodium chloride, which can be harmful to human health if consumed in large quantities. Desalination plants can be used to remove salt from seawater, but these plants are expensive to build and operate, and they require a significant amount of energy. As a result, desalination is only used in a few areas of the world where there is a scarcity of fresh water.

Freshwater sources, such as rivers, lakes, and groundwater, are the most common sources of drinking water. These sources are typically treated to remove impurities and contaminants before they are distributed to consumers.