The inlet to the waterwheel refers to the entire area from the trash rack to the inlet structure, the open channel and the water supply structure. There are four options for the water supply of an overshot waterwheel: sluice gates, the tongue inlet, and open channel supply without gradient or with gradient. Once the water jet has exited the opening the beam falls freely into the wheel (absolute path), until the cells rush through it. At the cell, the jet is divided into a portion falling freely into the cell and a portion striking the back of the blade. The free falling water particles of the jet move on a relative path because of the turning wheel. We show how to calculate the absolute and relative path of the water beam.