The fifth line holds the ruling place of the hexagram and makes the smallest possible claim from it. Legge's translation describes the water in the defile as not full enough to flow away, filled only to the border, and gives no error, while the commentary on the image observes that the greatness of the subject's work is not yet achieved. Nothing here is a triumph. The pit is level, the water is not spilling, and in a figure of doubled peril that is the whole of the good news and it is genuinely good news.
The stroke is strong, central and correctly placed, the only line in the hexagram to satisfy all three conditions at once, and it holds the middle of the upper trigram Kan. That combination is what permits containment. Water rising past its border floods whatever lies around it, and water that has not reached the border leaves the pit unfilled; this line stands exactly at the level where danger is neither spreading nor pretending to be over.
Read against the fourth line's improvised offering and the sixth line's entrenchment, this is the hexagram's model of what competence looks like in continuing danger. It does not promise an end to the situation, and the commentary is careful to say the work is not yet done. It promises that the situation is being held at its present size by somebody who is not trying to claim more than that.