Can you Dilute Beer after Fermentation?

One thing that most beginner homebrewers struggle with is having large enough equipment to make the amount of beer that they want, since most homebrewers start off with the typical 5-gallon (about 22 liters) brew kettle.

However, if you’re trying to brew using a “brew-in-a-bag” system, then it may be quite difficult to brew those full 5-gallons of beer with that same 5-gallon kettle, meaning that you will most likely end up with a lot less beer than you initially thought you’d be able to make.

Luckily, there’s a way where you can brew a more “concentrated” batch and then dilute it down with pre-boiled water, and this is called “high gravity brewing”, which essentially allows you to make more beer without the need of having to purchase larger equipment.

In this article, I will go into more detail about high gravity brewing, if you can add water to dilute the beer, its pros and cons, in what stage of the process water should be added, if it’s recommended or not, things to consider before adding the water, and more!

So, without any further ado, let’s get started!

What is high gravity brewing?

High Gravity brewing consists of creating a wort that has a higher than usual amount of fermentable sugars for the yeast to consume and to turn into alcohol, resulting in a stronger beer with a higher alcohol content. This higher gravity wort can then be diluted with water before the fermentation process begins to maximize production capacity without the need for a larger fermentor.

The principle behind high gravity brewing is simple: You create a wort that has an original gravity higher than the target and then you simply dilute it. Some people dilute the beer after fermentation, but common practice is to dilute the wort after the boil (before fermentation even begins).

It’s worth noting, however, that it’s also common practice to brew with a higher gravity simply to create a stronger beer with a higher alcohol content that is more flavorful and powerful, and not just to be able to make a larger batch by watering it down later on.

Pros of High Gravity Brewing

  • No need for larger equipment since you can dilute the wort.
  • More consistent results since you have full control of the wort’s gravity (which is why it’s used in commercial beer production).

Cons of High Gravity Brewing

  • Risk of wort contamination & oxidation.
  • You make the beer flavor softer.
  • Requires more specialized yeast strains.
  • Requires more hops.

As far as contamination goes, in order to prevent it, I’d recommend boiling the water for at least 15 minutes and to then let it sit and cool down in a sanitized pot before adding it to the wort.

Things to consider when adding water (Diluting):

  • Water should be pre-boiled for at least 15 minutes to sterilize it and to remove as much oxygen as possible. Then it must be cooled down to match the wort’s temperature.
  • Don’t over dilute.
  • Higher gravity brewing is more complicated and requires more yeast, hops, and overall stricter conditions to succeed.

Can you add water to beer after fermentation?

If you brewed a higher gravity beer and need to lower the alcohol content, then diluting it after fermentation with water is possible, although it’s worth mentioning that the dilution water must be thoroughly deoxygenated and that the risk of contaminating the beer can be quite high, so basic sanitation practices are a must.

Common practice is to dilute the wort (after the boil, before fermentation), and not the beer after fermentation is complete. While it still can be done, there are more risks involved.

If you decide to go this route, use a tube to add the water below the beer’s surface. This is to avoid splashing since it might introduce oxygen into the beer, which is not something we want, and also make absolutely certain to sanitize any equipment you use to add the water since you don’t want any bacteria to make its way into the beer as well.

When should you dilute the beer?

I already mentioned this previously, and it’s basically how high-gravity brewing works, since you add the pre-sterilized water to the wort before the fermentation process even begins (after the boil), and it’s the recommended way of doing things since it allows you to achieve much more consistent results over time, which is why commercial breweries use this method.

Additionally, adding the water to the wort before the fermentation, lowers the overall risks involved since introducing oxygen at this stage isn’t harmful because the yeast will consume it all, whereas introducing oxygen after fermentation has taken place will oxidize the beer, create off-flavors, lead to a lack of clarity in the beer, and lower its shelf life.

Use a dilution and Boil Off Gravity Calculator

A Dilution and Boil Off gravity calculator helps you find out how much you need to dilute or boil down your wort volume in order to hit a certain gravity.

These types of calculators are extremely useful when you want to achieve consistent results over and over again.


Can you add water to an already fermenting batch? It’s not recommended to add water during the fermentation process since it could create al sorts of issues. In fact, once fermentation has started, it should be left alone.

Is it OK to add water to the wort right after the boil? Adding water to the wort after the boil is what’s known as “high-gravity brewing”, and it’s the recommended way of diluting the wort since it allows you to have more consistent results when brewing, and it also prevents oxidation issues which may happen if water is added after the fermentation has taken place.

Can you Stir beer during fermentation? Stirring beer while it’s fermenting is not recommended since it can introduce harmful bacteria as well as oxygen into it, resulting in off-flavors and unwanted aromas, as well as a shorter shelf life. A better solution is to shake the fermentor a little, since this is more than enough to reactivate the yeast.


While you could dilute your beer after the fermentation process is finished, it’s not recommended and it’s not common practice. The way it’s generally done, and this is how commercial breweries do it, is to brew a higher gravity wort and to then dilute it before fermentation even begins.

This is to have more control over the end result, as well as to produce a lot more beer with smaller equipment.

I’d recommend diluting the wort (after the boil, before fermentation) and not once the fermentation is done, and especially not while fermentation is taking place, since you run the risk of introducing more oxygen at a point where it could cause more harm than good.

I hope this information was useful.

Have a great day!

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