Tevul Yom, Chapter Two, Mishnah Six
1) A jug which sunk into a cistern containing wine, and a tevul yom touched it:
a) If [he touched it] from the rim and inwards, it serves as a connective;
b) If from the rim and outwards, it does not serve as a connective.
2) Rabbi Yohanan ben Nuri says: even though [the level of wine in the cistern] is the height of a man [above the sunken jar], and he touched [the wine] directly above the mouth of the jar, it serves as a connective.
Section one: Our mishnah describes an open jug of terumah wine that sinks into a cistern containing hullin (non-sacred) wine. If the tevul yom touches the wine that is inside the rim of the jug, even if this wine came from the cistern, all of the wine in the jug is connected. The terumah wine will all be disqualified.
However, if he touches outside of the rim of the jug, then the wine is not connected to the wine in the jug, even if it is the same height as the jug and may indeed be intermingling. The jug in the wine remains pure and can be used as terumah wine.
Section two: Again, Rabbi Yohanan ben Nuri rules strictly concerning connectives. Even if there is a tremendous amount of wine in the cistern above the jug of terumah, the entire height of a man, and the tevul yom touched the wine directly above the jug, the wine above the jug and the wine in the jug are disqualified. Basically, this would seem to mean that the entire contents of the cistern are disqualified.
If he touched the wine in the cistern on the sides of the jug, the jug’s content would not be disqualified.