Solution:
The mixture of sand and water can be separated by sedimentation followed by decantation.A sedimentation is a form of separating substances. This process involves letting an insoluble substance (a substance that will not dissolve in a solvent) settle. Hence, sedimentation can be used for solid-liquid mixtures, where solid is insoluble. Such mixtures are called suspensions.
Decantation is the act of separating two immiscible substances by pouring off one component, whereas sedimentation is the process of settling or being deposited as sediment.
First, the mixture is taken in a glass. After some time, sand gets deposited at the bottom of the glass as it is heavier than water. This process is called sedimentation. Then the upper layer of clear water is poured into another glass known as decantation.