Computing using water goes back to the use of clepsydra, which is Greek for "stealing water." Since all clocks are astronomical computers in origin, clocks represent some of the earliest, complicated, computers. In the 20th century, we have the Soviet-era hydrointegrator based designs of Lukyanov, and the Phillips machine housed in the Science Museum in London. The Phillips machine was called MONIAC and is a wonderful mechanism to behold, as it still is turned on for demonstrations. We designed and built a water computer that is hybrid analog/digital. The analog components are the two water containers, the water reservoir, the 3D printed servo housing and gears. Michael Howell and David Vega in the Creative Automata lab worked in unison to design and implement the computer. The model implemented is that of the Lotka-Volterra (LV) predator prey model. The water column on the left side of the above figure represents the prey population level) and on the right side, the predator population. Water rises and falls in each column in accordance with the dynamics as calculated over time with LV. The electronics used includes two water pumps in the reservoir, 4 servos and gears (3D printed using Makerbot), and a TFT shield mounted on an Arduino Mega. The goal motivating us to create this water computer was to surface the dynamics of LV in physical form for enhanced communication and education -- holding the interest of the general public longer than would be possible with flat symbols and drawings. Subsequent models may be located within the ATEC building or in a local art or science museum. This is our first functioning tangible model prototype, and we have several others that will use this as a foundation. A video can be watched here. Water computing: welcome back to the future.