The reservoir is read as deep, stored feeling — calm on the surface, vast beneath. It stands for inner reserves and for what has been gathered and held back.
Has this come up in your dreams before? What was going on in your life then?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.