The article presents methods of evaluating energy consumption of water pumps. Pump characteristics during work at variable rotational speed and constant head are discussed. Characteristics of the upper slope of pump efficiency curve were determined for the cases of constant and variable growth of rotational speed The left-sided coefficient of pump efficiency correction was defined.

The article presents criterion of evaluating energy consumption of water pumping. The lower slope of pump efficiency characteristic curve was plotted for the case of: constant gain of rotational speed and variable gain of rotational speed. The unified form of the lower slope of pump efficiency characteristic curve was defined for variable head. The right-side coefficient of pump efficiency correction was defined.