reservoir

(noun) a large or extra supply of something. Examples: "A reservoir of talent."

(noun) lake used to store water for community use. Synonyms: artificial lake, man-made lake.

(noun) tank used for collecting and storing a liquid (as water or oil).

(noun) anything (a person or animal or plant or substance) in which an infectious agent normally lives and multiplies. Synonyms: source. Examples: "An infectious agent depends on a reservoir for its survival."