Water is filled up to a height $h$  in a breaker of radius$R$ . The density of water is$\rho$ , the surface tension of water is $T$  and the atmospheric pressure is$P_0$ . Consider a vertical section $ABCD$  of the water column through a diameter of the beaker. The force on water on one side of this section by water on the other side of this section has magnitude:

 

Consider water on one side of the vertical section $ABCD$  as the system.

Note that this is the half-cylinder. Draw the forces on this half-cylinder by another half-cylinder. 

At a depth below $x$  from the top surface consider a strip of width$dx$ . 

Force on this strip is$\left(P_0+\rho gx\right)\left(2Rdx\right)$ . 

Total force on one half-cylinder by the other half-cylinder is

$F={\displaystyle {\int }_0^h\left(P_0+\rho gx\right)2Rdx-2RT=\left|2P_{0}Rh+R\rho g{h}^2-2RT\right|}$