Water-powered clocks work by gradually dissolving a small fuel cell located inside the water tank of the clock. This cell provides enough energy to power the clock, and the water acts as a conductor to transmit the energy to the clock's connectors. Despite the belief that water functions as a power source for the clock, it actually generates power by moving energy throughout the structure.
The fuel cell located inside the water-powered clock is composed of a cathode, or positive charge, and an anode, or negative charge. In many clocks, both parts of the fuel cell are made of common metals such as copper for the cathode and zinc for the anode. When these two metals are immersed in water, electrons can pass between them, resulting in an electrical charge that is powerful enough to run the clock. The water then serves the secondary purpose of transporting electricity to power the clock.
A unique kind of water powered clock is located in New South Wales, Australia. The Hornsby Water Clock is a decorative fountain with a large bronze clock mounted on the front. The clock uses an internal water wheel to power the clock as water is pumped through the fountain.