Place Water Buckets or a Water Cell in the lower slot (or place the Water Mill inside water), and optionally an RE Battery in the upper slot. The Water Mill will charge the battery or output power at a rate of 2 EU/t (manned) or 0.010 EU/t per block of adjacent water (unmanned). The maximum output of an unmanned Water Mill is 0.25EU/t (3x3x3 cube of water with the mill in the middle, plus 1 piece of cable to direct the energy = 25 water tiles).
Note: In v.1.81 Water Cells do work in Water Mills
|Output|| Manned: 2 EU/t|
Note: In v.1.81 Unmanned Mode for Water Mills appears to be functioning
A Water Mill on its own will produce very little EU if left unmanned, even when completely surrounded in water. So it's better to build compact clusters of them. A 'water tower' is one of many methods.
A water tower is a number of watermills, usually stacked, such that they all feed to the same energy storage device and are surrounded by water. For best results, arrange the tower sections so that there's at least a one block layer of water around each watermill. Below is an example of a horizontal layer of a watermill.
A Water Mill only uses water that directly surrounds it (a 3x3x3 box with the Water Mill in the center). Each block of water adds roughly 0 EU/s to its overall output.
Using the water tower design from above will result in each Water Mill being surrounded by 21 water blocks like so:
Some notes about the behavior of some Water Mills that were studied:
- Water Mills can 'share' the same water block with seemingly no effect.
- Using flowing water instead of still water had no noticeable effect.
- A Water Mill suspended over water will still react to the water below it even though the watermill is not visibly touching the water.
- Water Mills are not noticeably affected by rainfall.