A typical water wheel can produce around 400 watts of power under normal circumstances. This is enough power to run three light bulbs and a typical television simultaneously. However, the output of any water wheel kit installation may be higher or lower depending on flow rates at a given time.
The minimal water flow requirements for a typical water wheel kit to produce reasonable amounts of power are around 20 gallons of water per second. It is possible to estimate a rough output power for a given installation based on the size of the wheel and the rate of water flow, though actual output is also affected by generator efficiency and whether or not the water wheel uses an undershot or overshot design.