These three verses began the third of four sections of this chapter (:15-19). They all represent advice from father to son – don’t get involved with immoral women.
Verse 15 talks about a privately owned cistern or well which most families had in their homes. With no plumbing in the ancient world, if we had our own water source that we could trust, it would be insane to go out and try to find good water somewhere else.
Verse 16 continues the thought, asking a rather rhetorical question – should I let my own water at my house overflow into the streets and squares of the city?
Verse 17 answers – don’t do it!
But the issue here really isn’t water – it’s an analogy. In symbolic poetic language, within the context of ancient city life, a husband is supposed to stay home appreciating his wife. He should not take that which belongs at home out into the street looking for one of those women discussed in this chapter.
Of course, the whole chapter is guy talk – father to son (:1, 7, 20). Mom could have said the same thing to her daughters about the boys!
While our section (:15-19) doesn’t discuss consequences, there are plenty. In fact, almost half the chapter is an explanation of those consequences (:4-6, 9-14, 21-23).
We have a modern wise saying that about sums up this whole section – “the grass is always greener on the other side” — Not!