GEMARA

(Mishnah - R. Akiva): Redness mixed in a Baheres looks like redness in k'Sid. Their color is like wine mixed with water.

Bava Basra 96b (Beraisa): One blesses sheha'Kol on dregs of wine;

Others say, if the dregs have the taste of wine, he blesses Borei Peri ha'Gafen.

(Rabah and Rav Yosef): The Halachah does not follow 'Others'.

(Rava): All agree that if one put three measures of water on the dregs and four measures of liquid come out, it is considered wine;

This is like Rava taught elsewhere, that if one measure of (raw) wine cannot be mixed with three measures of water (lest the mixture be too weak), the (raw) wine is substandard.

(Rava): All agree that if one put in three measures and three come out, it is considered water. If he put three, and three and a half come out, Chachamim say that the same water came out, and a half-measure from the dregs. There is six times as much water as dreg-wine, so this is not wine. Others say that two and a half measures of water came out, and one from the dregs. There is two and a half times as much water as dreg-wine, so this is wine.

Avodah Zarah 73b (R. Ami citing R. Yochanan): If two cups of diluted wine, Chulin and Terumah, got mixed, we ignore the Chulin wine, and the water is Mevatel the Terumah.

Shabbos 76b (Rav Nachman): One must put a quarter Revi'is of (raw) wine in the Kos of Berachah, so that after it is mixed there will be a Revi'is.

Objection (Abaye - Mishnah): (Dam Nidah is Tamei if it is the color of) two measures of water mixed with one measure of Sharoni wine.

Answers (Rava): Sharoni wine is weaker than regular wine. Alternatively, for drinking it is proper to mix wine with three measures of water, but this is not the right color to compare to Dam Nidah.

RISHONIM

Rif (Berachos 32b): The Halachah does not follow 'Others'.

R. Yonah (DH Shemarim): If one put three measures of water in and four came out, it is proper wine, so we bless Borei Peri ha'Gefen. If less than four came out, even if it has the taste of wine, one does not bless (Borei Peri ha'Gefen, only sheha'Kol). It seems that when four came out it is considered wine regarding their wines, which were strong. Where wines are not so strong, we do not consider it wine and bless Borei Peri ha'Gefen even if four came out. Perhaps this is why the Rif did not explain this, and Stam said that the Halachah does not follow Others.

Rambam (Hilchos Berachos 8:9): If one put three measures of water on dregs and four came out, he blesses Borei Peri ha'Gefen, for this is mixed wine. If less than four came out, even if it tastes like wine, he blesses sheha'Kol.

Rosh (Avodah Zarah 2:13): Yayin Nesech applies to mixed wine as long as it tastes like wine. Regarding dregs, we distinguish between when three measures come out, and when three and a half come out, regarding Borei Peri ha'Gefen. That is because a mere acidity comes out of dregs, even if it has the taste of wine. People dilute pure wine according to their nature and custom. Therefore, Yayin Nesech applies as long as it tastes like wine.

POSKIM

Shulchan Aruch (OC 204:5): If one put three measures of water on dregs and he found four measures of wine, this is like mixed wine, and he blesses Borei Peri ha'Gefen. If he found less than four, even if it has the taste of wine, it is mere acidity and he blesses sheha'Kol. This refers to their wines, which were strong. Our wines are not so strong, so even if he put three and found four he does not bless Borei Peri ha'Gefen. It seems that we estimate according to how people mix wine in that locale.

Beis Yosef (DH v'Al): Since the Halachah does not follow Others, we bless Borei Peri ha'Gefen only when four came out. R. Yonah says that this is only for their wines, which were strong. This seems correct.

Gra (15 and YD 123): Most Poskim hold that it is wine only when he put three and found four. Regarding Yayin Nesech, we are concerned until it is diluted with six parts of water. That refers to (diluting) proper wine (not just dregs). The Rema discusses diluting proper wine. He learns from Avodah Zarah 73b. The cups were mixed normally, three parts of water for each part of wine. The cups are equal size. In all, there are six parts of water against the Terumah. We ignore the Chulin wine, and the Terumah wine is Batel in six parts of water. Normally, Min b'Eino Mino (when mixed with another species), Terumah is Batel in 60, like other Isurim. Wine is Batel in six parts of water, for it does not improve the water. It is detrimental, i.e. Nosen Ta'am li'Fgam, which is permitted regarding all Isurim.

Gra (16): Sharoni wine must be diluted with less water, for it is weaker, and all the more so our wine!

R. Akiva Eiger: If between three and a half and four came out, the Rashba and Ran argue. We bless sheha'Kol due to Safek. For the Berachah Acharonah, one should drink proper wine and bless Al ha'Gefen, and this exempts the Safek.

Mishnah Berurah (32): If one diluted pure wine with almost six parts of water, it is proper wine as long as it tastes and smells like wine, and people drink it mixed this way, in place of wine. If not, we follow most people and ignore one who drinks this.

Kaf ha'Chayim (32): Olas Tamid says that nowadays that our wines are weak, we do not mix them with water at all, so if water was mixed in, even less than the amount of the wine, one does not bless Borei Peri ha'Gefen. This requires investigation. Eliyahu Rabah says that this is why the Levush omitted the Rema. Eshel Avraham says that for our wines, if there is more water, one blesses sheha'Kol. This implies that if they are equal, one blesses Borei Peri ha'Gefen. One should be careful to avoid a majority of water, even in pressed circumstances, i.e. he has only a little wine.

Rema: This is only if the wine is not less than one part in six of the water. If it is, it is surely Batel.

Beis Yosef (DH Kosav ha'Agur): The Agur says that even though normally, R. Tam rules like Ta'am k'Ikar (something that absorbed taste is like the matter itself) is mid'Oraisa, even to be lenient, regarding Berachah, one in six is not considered taste. It is Batel regarding Berachah. If it is more than one part in six wine, it depends on the taste. If people normally drink it in place of wine, one blesses Borei Peri ha'Gefen.

Magen Avraham (16): Regarding wine in water, it is not considered taste unless it is at least one part in six. If it is at least one part in six, if it is proper to drink such a diluted wine, and people drink it in place of wine, we do not say that his opinion is Batel to that of everyone else. The Taz (YD 114:4) says that wine is Batel also in six parts of other liquids. I say that only (this ratio of) water ruins wine. Also Isur v'Heter says so. However, our wines are surely Batel (in six parts of other liquids).

Mishnah Berurah (31): The Mechaber holds that our wine can be diluted only with less than three parts of water, even if people drink it like this, for wine of the Gemara can be diluted only with three parts of water. The Rema connotes that (also the Mechaber) allows almost six parts of water for one part of dregs! The Agur said so only regarding diluting pure wine.

Shulchan Aruch (272:5): One may say Kidush over pure wine, even if it is strong and can be diluted with three parts of water. It is better to dilute it properly.

Rema: Our wines are better unmixed.

Beis Yosef (DH u'Mah she'Chosav umi'Kol): This is obvious, in order that it will be pleasant to drink.

Kaf ha'Chayim (31): The Ari Zal says that based on Kabalah, one should mix the wine. Since our wines are better unmixed, one should add only three drops to fulfill the Kabalah.

Minchas Shlomo (1:4): If one adds four parts of water for each part of grape juice concentrate, he does not Borei Peri ha'Gefen. We bless sheha'Kol on overdiluted wine, and it tastes like wine more than reconstituted grape juice. One could say that the concentrate is primary, and the water is secondary, and since one must mix in much water, we bless Borei Peri ha'Gefen, just like on Konditon, which is a third wine (and a third honey and a third peppers. Wine is the minority, but the rest is to improve the wine.) However, grape juice is Borei Peri ha'Gefen only because it is destined to be wine. We say Borei Peri ha'Gefen on wine only because it was changed for the better; it gives sustenance, and gladdens. Grape juice does not gladden; letter of the law, one may drink grape juice at the meal before Tish'ah b'Av. According to this, if one made wine essence and added even 100 parts water to the wine concentrate, if it returns to tastes like wine, perhaps he blesses Borei Peri ha'Gefen, just like we bless Borei Peri ha'Gefen on wine diluted with three parts of water. We do not say so for reconstituted grape juice. It is unlike a k'Zayis of Chelev or Neveilah that shriveled in the sun to less than a k'Zayis, and rain came and it returned to a k'Zayis. One is Chayav Kares or lashes, for the same matter inflated again.