Water (fluidic) computer
Realizes: binary addition / boolean logic (AND, XOR)
Water levels in vessels encode binary digits; a siphon and slow drain combine to implement AND and XOR in a single cup-and-tube unit. A filled cup is a 1, an empty cup a 0. When two cups feed one container the siphon trips (AND = carry), while the remainder leaks out the XOR drain. These half-adder cells chain into a multi-bit ripple adder. No moving parts beyond the water itself. Speed: seconds to minutes per bit (gravity-driven flow). Capacity: 4-bit addition demonstrated; theoretically scalable.
Examples
I Made A Water Computer And It Actually Works
Build and demonstration of a fluidic binary adder using cups, tubes and siphons to implement AND and XOR gates in water
Hackaday — Logic Flows, Literally, In This Water Adder
Technical write-up explaining the siphon-based AND/XOR mechanism and how the cells chain into a multi-bit adder