How do I lower the alcohol content of my beer

Question

I brewed from a kit and the beer is ready to bottle. The alcohol level is 7 and I would like between 4 and 5. I can't change the yeast or sugar content at this point. Could I just add water?

Answer 1

Yes, just add water. But remember, it’s going to dilute everything, not just the alcohol.

And you’re risking contamination.

For the sake of limiting contamination, you should use distilled water from the store. But then you’ll even be diluting electrolytes in the water. Buy water that’s been distilled, but had electrolytes added back. That should somewhat help.

You’re sure it’s 7%? What was the starting gravity, and what did the kit say the final ABV was supposed to be?

Answer 2

You can lower the ABV of beer by adding water. In the homebrew world, you want to do this "gravity adjustment" prior to fermentation. The reason to do it early is that adding water will add oxygen to your beer. Oxygen before fermentation is fine (good in fact), while oxygen at bottling time is bad and will decrease the shelf life of your beer.

This is referred to as a gravity adjustment because you are adjusting the specific gravity of your wort. You measure the specific gravity of your wort and determine the amount of water to add in order to lower the gravity to your target.

It is common to intentionally perform "high gravity brewing" where the brew house limits our volume that we can produce. By producing as big a batch of higher-gravity wort as the brew house allows, but then adding water on the way to the fermenter allows for a larger final batch (e.g., up to 25% more).

Some recipe adjustments might be required, since wort density can affect hop utilization.

Big brewers have the ability to do gravity adjustments at packaging time, because they have equipment that can deliver precise amounts of sterile, deoxygenated water.