In which type of water storage system does water generally "float" on the storage system?

In water distribution systems, operating storage refers to the volume of water that is regularly used and kept available for system operations, maintaining a constant supply for daily use. In this context, the term "float" can be related to how the water level fluctuates within this type of storage. Operating storage facilities, such as elevated tanks or reservoirs, maintain levels that can rise and fall based on daily consumption patterns, similar to how water levels "float" within the tank.

While pressure storage, emergency storage, and hydropneumatic storage serve important functions within water systems, they do not typically involve the same dynamic level fluctuations described in the context of operating storage. Pressure storage is primarily focused on maintaining water pressure in the distribution system, not on accommodating daily usage. Emergency storage is kept in reserve for unexpected situations, such as emergencies or outages, and may not reflect regular operational patterns. Hydropneumatic storage combines water and air to manage pressure but does not emphasize the floating aspect of water levels related to daily consumption. Thus, operating storage is the most fitting choice in relation to the phenomenon of water "floating" due to its dynamic interaction with consumption demands.