פירוש על עבודה זרה 116:11

The story is fascinating—we can see that the rabbis didn’t always know who was Jewish and who was not. After having poured the wine, the rabbis debate whether Jews may drink the wine, meaning it is totally permissible, or whether they may not even sell it, meaning it is totally forbidden.

The sugya here explains why the non-Jew did not know that it was not wine. It was night and it was new beer.

The Talmud raises another difficulty. If the non-Jew drew the wine from the casket, then he touched the wine with the drawing cup. And even though he did not know that it was wine, he still directly acted upon it, and it should be prohibited.
The resolution is that the non-Jew did not touch it directly. He only poured it. And according to this sugya, there is a principle that whenever a non-Jew pours wine without intention (meaning he does not know it is wine), the wine is permitted. Note that in this case there are two reasons to be lenient: 1) he does not know that it is wine—meaning it is unintentional; 2) he did not touch it. He only poured it.

Asi asks whether wine mixed with water by an idolater is prohibited. The idolater has not touched the wine, he has only poured it in order to mix it.
Yohanan responds by criticizing R. Asi for his choice of verbs. Mesakho is the biblical verb, whereas the rabbis use the word “mezago” with the zayin replacing the samekh. There are many cases in which the language the rabbis use is not identical to the biblical language. Hebrew had after all been developing for thousands of years. These two roots are actually quite close, clearly related one to the other.
In any case, R. Yohanan answers that while such wine is not strictly prohibited, it is advisable that Jews avoid this situation. This is like a nazirite going into a vineyard. There is no prohibition but it is better that he avoid it lest he come to eat the grapes.

In these two pieces we can see that rabbis prohibited Jews from drinking wine mixed by non-Jews. Although the principle “Go, go, we say to the Nazirite” is sometimes understood merely as good advice, here it is understood as creating an actual prohibition.

Shimon b. Lakish believes that the people he sees are committing two errors—they are eating produce that should have been tithed, and they are drinking water that is prohibited.
Yohanan disagrees on both counts and sends Resh Lakish back to Botzrah to let the people know that he had erred in his ruling. First of all, Botzrah is not Betzer. Betzer is mentioned in Deuteronomy 4:43 and is part of Israel. Since it’s not part of Israel, the people there do not need to tithe. Second, the water is not prohibited. The Talmud will now explain why.

According to R. Yohanan, water belonging to the public cannot become prohibited, even if people worship it.