Concept: Hydrostatic Law: The pressure at any point in a fluid at rest is obtained by the Hydrostatic Law which states that In an incompressible static fluid column, the rate of increase of pressure in a vertically downward direction must be equal to the specific weight of the fluid at that point.
dP
dh
=ρg ∫dP=ρg∫dh P=ρgh where P = pressure above atmospheric pressure and h = height of the point from the free surface.