IS:10313-1982:-  Indian standard requirements for the setting tank (clarifier equipment) for the water treatment plant.

Settling tanks (sedimentation tanks, sedimentation basins, or clarifiers) are used in water treatment 10 to reduce the amount of settleable solids which are present in water.

Sedimentation usually finds application in two principal ways in water treatment, that is, plain sedimentation and sedimentation following coagulation, flocculation, or softening.

Plain sedimentation is used to remove settleable solids that occur naturally in surface waters. These solids settle without any previous treatment. Plain sedimentation is usually needed a preliminary process to reduce heavy sediments prior to subsequent treatment processes such as coagulation. This is often referred to as pre-sedimentation or primary clarification.

Sedimentation following chemical coagulation and flocculation is used to remove suspended solids that have been rendered settleable by chemical treatment.

Factors that influence sedimentation are:

1. Size, shape, and weight of the particle
2. Viscosity and temperature of the water
3. Surface overflow
4. Surface area
5. Velocity of flow
6. Inlet and outlet arrangement
7. Detention periods
8. The effective depth of basins.