Genesis: In Genesis 1 we read of the waters above the earth. Here in Genesis 6 we see rainfall for the first time. Until that time it is speculated that the earth was adequately watered perhaps by dew. Accordingly, the underground springs also burst forth at the command of God. So God saved a remnant of both (human and water) to repopulate the face of the earth, but also to carry forth His word.
Gospel: Luke 11:37-52
New Testament: Revelation 12:1-6
Old Testament: Genesis 6:13-22