For time-periodic two-dimensional water waves of small amplitude, it is shown that a static balance exists between the mean dynamic pressure force at the bottom, the gradient of the mean sea level, and the divergence of the radiation-stress tensor. The balance holds for quite arbitrary wave pattern and bottom variation so long as dissipation and steady currents are insignificant. This is the further generalization of a result obtained by Longuet-Higgins (1972) for the gradual refraction of a progressive wave where the bottom pressure is unimportant.