Can I Make Wine From Grape Juice That Was Diluted With Water?

I purchased a winemaking kit that came with fresh juice from a local winery. The process was not explained well in the class, and it turns out I added water to the fresh juice in error (instructions did not differentiate between fresh and concentrated juice). The juice does contain 50% water, and has been in the refrigerator since (about 2 months). Is this juice still usable to make a batch of wine? If so, is it worth it since it is watered down? I don’t even know if adding water to the fresh juice is okay to produce an okay wine? Thanks for any and all help!
Name: Keith S.
State: NY
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Hello Keith,
Yes, you can make wine from grape juice that has been diluted with water. It will just have a lighter-bodied wine..
The bigger issue is putting together a wine recipe that will work with grape juice and water. Along with the grape flavor, the acid was cut in half; the nutrients were cut in half; and the sugar was cut in half. These deficiencies will need to be compensated for within a new, adjusted wine recipe.
Acidity or tartness is a major flavor component of any wine. If the wine’s acidity is too low, it will directly result in the flavor of the wine. The wine will taste flat and insipid.
Lack of nutrients can effect how vigorous the fermentation will be — not enough nutrients, you can have fermentation that slowly drags on forever.
With this in mind, what I would suggest doing is adding 4.5 teaspoons of Acid Blend for every gallon of water in the juice. This should get the acidity level back up to a reasonable range. Alternatively, you can use an Acid Test Kit to measure your wine must’s acidity level and know exactly how much Acid Blend you will need to add to get to an optimal level.
You will also need to add 1 teaspoon of Yeast Nutrient for each gallon of water added. The Yeast Nutrient will work along side the nutrient from the grape juice to supply a rich form of nitrogen to the fermentation and help it to go faster.
The addition of Wine Tannin is optional, but I would suggest 1/4 teaspoon for each gallon of water that was added to the wine must. This will help with the body and pH balance of the wine. It will also help with the clarification of the proteins from the grapes after the fermentation has completed.
Finally, you will need to add sugar to the wine must. Sugar is what the wine yeast consume to produce alcohol. The simple math is that the less sugar you have in the fermentation, the lower your resulting alcohol will be. In general, a grape juice will have enough sugars in it to produce around 10% to 14% alcohol. Since your grape juice is diluted with water by half, it will only produce 5% to 7%, as is. This is why you will need to add sugar to the wine.
A simple calculation is to add 2 pounds of cane sugar (4 Cups) for every gallon of water that was added to the grape juice. This could be pushed up to 2-1/2 pounds (5 Cups) but no more.
It is important to point out that even though the grape juice was diluted with water by half, the flavor was not cut in half. This is because of the way we humans perceive things. According to our taste-buds, the flavor of the wine will be weaker, but only marginally. So don’t feel like you will have an inferior wine simply because the grape juice was diluted with water. Many lighter-bodied wines taste wonderful.
Happy Winemaking,
Customer Service at E. C. Kraus
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Ed Kraus is a 3rd generation home brewer/winemaker and has been an owner of E. C. Kraus since 1999. He has been helping individuals make better wine and beer for over 25 years.