The invention relates to a water wheel, preferably an undershot or breast-shot water wheel having a horizontal hub (21), wherein paddle arrangements (15) are provided along the wheel circumference (22) for converting the kinetic and optionally also potential energy of the water stream into a rotational motion of the water wheel, wherein the paddle arrangements (15) comprise at least two paddle blades and the paddle blades have different sizes, characterized in that the outer paddle blade (13) has a greater depth (23) than the further inner paddle blades (14, 16, 17) of the paddle arrangement. The invention further relates to a hydroelectric power plant comprising one or a plurality of such water wheels.