A sand treatment plant is a mechanism for filtering impurities that consists of a sand tank through which water circulates. The sand acts as a natural filtering agent, capturing any impurities in the water to purify it and ensure its quality.

A mixture of sand and water can be separated by the process of sedimentation and decantation. First, the mixture is allowed to stand undisturbed. The heavier sand will settle down then the clear liquid is transferred to another beaker carefully without disturbing the sediment.

The water is then allowed to settle in a tank, where particulates such as faeces (known as sludge) settle at the bottom and are scraped away using a scraper.