I would like to double the size of my batches from 5 gallons to 10 gallons without changing equipment.

For example, let's say I have a 5 gallon recipe for an IPA. I know my mash cooler is big enough to mash at least double the grain bill for my 5 gallon recipe (I have brewed 5 gallon batches of strong ales which easily have more than twice the grain of my 5 gallon IPA recipe).

If I mash twice the grain for my 5 gallon IPA recipe, then just boil the ~6 gallons of wort (and double the hop additions), can I then split the higher OG 5 gallons of wort into two fermenters (2.5 gallons in each) and top off each fermenter with another 2.5 gallons of distilled water each?

I know mash and boil times will be extended due to the higher grain/OG, but is there anything inherently problematic with "watering" down a higher concentration wort to double the batch size?


5 Answers 5


This has been done before. Essentially you are brewing a high gravity wort and diluting it. I understand some large breweries do the same. This article from More Beer has some thoughts on it. They recommend no more than a 30-40% dilution - not 100%


High gravity brewing is a technique used by the giant macro brewers of adjunct american lager. They'll brew a high gravity wort, and add water in the fermenters. I first heard this from Mitch Steele of Stone at the time, who had worked for Anheuser-Busch making Budweiser. His interview on Brewing Network The Session from 11-05-2006 described the way they did it when he worked there in the 1990s.

The clear advantage to the technique is economies of scale. They can brew concentrated batches and increase their total output by adding cool water. Not only does it save on energy to mash and boil, but also saves on cooling expenses. The drawback is loss of flavor. Hop utilization could decrease at higher gravities too, but they aren't typically doing hoppy beers.

At a home brew level, you are limited by the size of your mash and boil kettle when going for a double batch. There is nothing wrong with your water-down idea. It works but you might loose some of your beer's flavor potential. Since your mash tun is large enough for a double-batch of regular strength, you must be lacking boil kettle room for a double batch? You can upgrade to a 15.5 gallon converted keg for a budget option. That is pushing it because you're using up to 13 gallons pre-boil, so you have little room for foam. If you try it I recommend a spray bottle and perhaps some anti-foaming agent, then really keep an eye on it when it starts boiling, but its totally do-able.


This is something that is commonly done, and I have done it myself many times. A lot of extract recipes call for a partial boil with water added to make the final volume. The main thing you need to take into account is your hop utilization. Boiling them in the highly concentrated wort will decrease the solubility, so you will need to add more than double the hops to get the same IBU.


Liquoring back can also be used to control the OG in your brews if you have overshot your FG then adding a little liquor to the finished wort is a widely accepted practice.

To expand the volume I would follow uSlackr's advise and not go beyond 30% to extend your brew length, as you don't maintain the quality of the brew much beyond this.

I would not liquor back with distilled water, that is an unnecessary expense, you can liquor back perfectly well with boiled and cooled water, the boiling drives off the chlorine, and drops out excess carbonates, but retains some of the trace minerals that your yeast needs as micro-nutrients.

Here is a calculator to help with this:http://www.brewheads.com/newvolume.php


I would recommend instead of watering down. Make a10 gallon batch. Then use 2 carboys.Pitch 2 separate yeast batches. I think that's the safest way to save the integrity of the Beer. For me the integrity of the Beer is the top priority for me.

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