What type of energy does water have when it is not moving?

Water that is not moving possesses potential energy. This form of energy is related to the position of the water, which may be determined by its elevation relative to a reference point, such as sea level. The potential energy of water can be thought of as the stored energy associated with its position in a gravitational field.

For example, a body of water held in a reservoir at a certain height has potential energy because it has the capability to flow downward under the influence of gravity if allowed to move. This stored energy can be converted to kinetic energy if the water is released, allowing it to flow and do work, such as generating electricity in a hydroelectric power station.

Kinetic energy, on the other hand, is the energy of motion, which does not apply to stationary (not moving) water. Thermal energy relates to the temperature of the water and the energy associated with the movement of its molecules, which is distinct from the concept of potential energy. Mechanical energy encompasses both kinetic and potential energy, but since the question specifically asks about water when it is not moving, potential energy is the most accurate description.