Which type of force acting on water tank wall ?

Hi, forces acting on the water tank is very important for the designing of the tank. The question you asked, needed an answer in details to understand what are the forces and how it is activated on walls of the tank.

Generally, there are three types of water tanks conditions exist

1. Underground water tank: in this case, hydrostatical pressure acts on the wall. Weight of surcharge acts on the tank. When the tank is empty, the surrounding pressure of soil external walls. Because of its expansion and contraction properties.
2. Water tank at some elevation: hydrostatic pressure due to water with gravitational force is acting on walls.
3. The water tank on the ground: only the hydrostatic pressure of water acting on walls.

Water tanks may be rectangular or circular in the section which has flat bottom when it is resting on the ground for underground. But if the tank is at some height bottom may be flat or conical in shape.

For design consideration please refer IS 456:2000.