The piezometric head in a static liquid: 

Explanation:

The total energy of a flowing fluid can be represented in terms of head, which is given by

The sum of the pressure head and hydrostatic pressure head is called the piezometric head. It is given by 

Piezometric head = 

where = pressure energy per unit weight or pressure head

= kinetic energy per unit weight or kinetic energy head

z = potential energy per unit weight or elevation head

The pressure at any point in a static fluid is obtained by Hydro-static law which is given by -

∴ P = -ρgz

∴ P = ρgh

where P = pressure above atmospheric pressure and h = height of the point from the free surface.

At point A, pressure head =  = hA  and datum head = zA

At point B, pressure head =  = hB  and datum head = zB

Piezometric head at point A =  = hA + zA = H

Piezometric head at point B =  = hB + z₀ = H

∴ piezometric head remains constant at all points in the liquid.