Seeing a reservoir in a dream can symbolize the depth of one’s unconscious. It might also represent memories, emotions and deep desires. It means you are caring for someone more than you should be and maybe even neglecting your own needs and you need to say what you want to them before forgetting again.
Also, a reservoir in your dream can represent desires, happiness, and childhood memories including areas that can be explored at a later time, such as places collected from various memories and travels.