The Overshot wheel is the most efficient of the watermills, it does however require a head of water from a higher point in order to power the wheel from above whereas the undershot wheel relies on the current to push the paddles & thus turn the wheel .
The overshot wheel has troughs or buckets which fill up one by one & it is the weight of the falling water filling the troughs which actually turns the wheel.
The mill need not be built actually alongside the stream as the water can be diverted via a leet or channel from quite a distance provided there is sufficient gradient to enable the flow.
The mill featured here also has a small millpool directly behind the mill which stores sufficient water to run the mill if the supplying stream is a little slow in times of drought.
The sluicegate can be seen and also a bypass sluice is fitted as this helps to control the flow of water in times of heavy rain.
This would be a small village mill where locals would take their corn to be ground into flour.
A pair of pigs can be seen below the bypass sluice & these would be another source of income for the miller