This is the correct way. In the water analogy, the circuit is a closed system and components are completely filled with water at all times. For example, the cap

This is the correct way. In the water analogy, the circuit is a closed system and components are completely filled with water at all times. For example, the capacitor is a filled sphere with a rubber divider. The total amount of charge/water is constant, but you can change how it is divided between the two plates by an applied voltage/pressure.