The concept of high-gravity brewing and dilution is not a secret in the professional brewing community. However, for home brewers attempting this method, there are a few important points to consider before getting started.
The Dilution Point:
Extract brewers are familiar with dilution. Almost every extract brewer boils concentrated wort and transfers it to a fermentor containing several liters of water to speed up the cooling process. Additional water is added later to reach the final batch volume. In this article, I propose adding water to the finished beer after fermentation. This method of dilution allows you to exceed the nominal capacity of your fermentor.
High-gravity brewing is only practical when producing average to medium-strength beers. Strong beers rely on the gravity obtained from malt, and diluting these beers would be counterproductive. There is also a limit to the amount of grain that can be used in the mash tun, so smaller batches with primarily the first runnings from lautering would need to be produced. Additionally, brewing yeasts have limits to their alcohol tolerance, making it practically impossible to brew extremely high-gravity beers (>12% alcohol by volume) for dilution purposes. Therefore, I suggest that high-gravity brewing with dilution should be applied to producing finished beers with target alcohol contents of up to 8% (v/v).
If you have ever been on a tour of a large commercial brewery, you may have tasted their undiluted beer and noticed its great flavor and character. Professional brewers can indeed make good beer! However, they often go overboard with water additions. Beer can only be diluted to a certain extent before it starts to taste watered down.
The general rule in the brewing industry is that beer can be diluted up to 30-40%. If we consider this range as the practical limit (and an extreme that most of us would want to avoid), then adding less water will have a minimal effect on the final product. With the right recipe adjustments, adding 10% water to your beer will make little difference in most people’s perception of the beer, while significantly affecting your production capacity. For example, if you use a conservative 20% dilution, you could increase a 5-gallon batch to 6 gallons. This means you can produce as much beer in five batches as you did in your last six.
High-gravity brewing requires larger quantities of every ingredient to match the characteristics of a normally brewed beer – more malt, more hops, and more yeast. High-gravity brewing also presents new challenges for brewers. Studies have shown that high-gravity beers, whether diluted or not, have poor head retention compared to beers of normal gravity. It has also been observed that high-gravity environments reduce hop utilization and cause some yeast strains to underperform. Adjustments may also need to be made for color. Fortunately, these problems can be addressed through recipe adjustments. The water used for dilution is also crucial, especially since it is added after fermentation.
Good Water Makes Good Beer
The water used to dilute your beer must be sterile and free from unwanted elements, including chlorine, oxygen, and possibly minerals. You can prepare your own water at home by boiling and cooling it in advance. Any oxygen in the water will oxidize compounds in the finished beer, reducing its shelf life and creating off-flavors. Boiling effectively removes oxygen from the water. After boiling, try to cool the water quickly to minimize its exposure to air (oxygen). When transferring the water (and beer) to avoid introducing air, do so carefully. This is less of a concern for bottle-conditioned or kegged beer because the yeast acts as a natural oxygen scavenger. However, the presence of air in beer should be avoided as much as possible, just like microbial contaminants.
In theory, carbonated water is the best type of water to use for diluting beer because it is oxygen-free and will not affect the carbonation of your beer. However, some carbonated waters contain sweeteners, salts, or other undesirable ingredients. If the beer is going through a secondary fermentation in the bottle or in a keg to achieve carbonation, carbonated water is not necessary.
Bottled distilled water is always a good option and that’s what I use. Most bottled drinking water brands have few or no microbial contaminants and are suitable for dilution. I always avoid mineral waters because of their mineral content and some brands are aerated. Pure drinking water from a machine should also be avoided due to variable mineral content and quality control (you can’t trust the water near the time a new filter is due).