What is the simple subject of following sentence sources water were not easily found?

The simple subject of the sentence "Sources of water were not easily found" is sources.

Here's why:

* Subject: The subject of a sentence is the person, place, or thing that performs the action.

* Simple Subject: The simple subject is the main noun or pronoun that performs the action.

In this case, "sources of water" is the complete subject, but "sources" is the core noun that is performing the action of "not being easily found".