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Gravity hydropower converters include hydrodynamic screws and gravity water wheels (Quaranta and Revelli 2018). Gravity water wheels are classified into three types (based on the head differences and the maximum flow rate per metre width), namely overshot, breastshot and undershot. Efficiency of gravity water wheels ranges between 75 and 85% (Quaranta and Revelli 2018), and their cost is lower than that of Kaplan turbines and hydrodynamic screws. With improved designs owing to recent developments, these hydropower converters are becoming cost‐effective and the effect on fish migration is decreasing along with better efficiency. Installation of these water wheels at old mill sites and in canals leads to electricity production which makes them more profitable (Quaranta and Revelli 2018). The hydrostatic pressure machine (HPM) and the turbine water wheel (TWW) are the examples of the novel water wheels which are in their primary stage. Hydraulic efficiency of HPM is 60–65% with an advantage of using running water without any canal drop (Kougias et al. 2019). The TWW finds its usage in head differences (up to 6 m) of an overshot water wheel and flow rates (few m³s⁻¹) of an undershot water wheel (Helmizar 2016).