Pneumatic positioning actuators are commonly used to control process control valves in petroleum, chemical, and paper industries. Pneumatics has many advantages in these applications, but there are also drawbacks. The purpose of this study is to find out if low-pressure water hydraulics can be used in the control applications of process valves. Low-pressure water is available in some process industrial applications. However, water hydraulics is considered very expensive technology. Some feasibility studies claim, though, that low-pressure water hydraulics is relatively cost effective. In this paper advantages and drawbacks of pneumatic and low-pressure water hydraulic solutions are discussed. Design, modeling, simulation, and experimental results of the low-pressure water hydraulic control of a process valve are presented. The performance requirements of a low-pressure water hydraulic servo valve are studied in simulations and experimental tests. Evaluation of the feasibility of water hydraulics in positioning applications of process valves is discussed.