Which water storage system utilizes compressed air to enhance water pressure?

The hydropneumatics water storage system uses compressed air to enhance water pressure effectively. In this system, a tank is partially filled with water while the remainder of the tank's volume is occupied by compressed air. As water is drawn from the system, the pressure from the compressed air pushes the water out, allowing for greater delivery pressure and consistent supply even during peak usage. This mechanism makes hydropneumatic systems particularly useful in applications where maintaining steady water pressure is crucial.

In contrast, pneumatic systems generally focus on the use of air pressure for various applications but may not incorporate the water storage function as specifically as hydropneumatics does. Gravity-fed systems rely on the force of gravity to deliver water, often requiring a substantial elevation difference, which is not related to the use of compressed air. Vacuum systems utilize negative pressure to move fluids, which fundamentally differs from how hydropneumatics operate. Thus, the unique feature of utilizing compressed air to enhance water pressure defines hydropneumatics as the correct answer.