The quiescent settling of water in reservoirs or lakes without the aid of chemicals is known as what?

The quiescent settling of water in reservoirs or lakes without the aid of chemicals is referred to as plain sedimentation. This process involves the natural settling of suspended particles due to gravity when the water is allowed to sit undisturbed. In plain sedimentation, the water naturally clarifies as heavier particles settle to the bottom over time, making it a straightforward and passive method of water treatment.

Coagulation, in contrast, involves adding chemicals to water to promote the aggregation of particles, making them easier to remove. Settling is a more general term that could refer to various processes, including those aided by chemicals, while flocculation specifically describes the process where particles cluster together into larger aggregates, often following coagulation. Therefore, plain sedimentation distinctly describes the specific phenomenon of natural settling without any chemical intervention, establishing it as the correct terminology for this process.