I’m not exactly sure why homebrewers settled on 5-gallon (19 l) batches; it may be related to soda keg sizes and manageable carboy volumes. Like most brewers, I just fell into line and never thought much about it until I started looking into improving my brewing setup. Stepping up to a 10-gallon (38 l) system barely changed the price over a new 5-gallon (19 l) setup, so it was a no-brainer. Of course, once you have twice the capacity, you might as well take advantage of it.
It turns out that the work differential is a lot like the initial cost of the equipment. For about 1.25 the effort, you can end up with twice the beer. Heating the hot liquor or getting a boil underway takes a bit longer, but that just gives you time to sip a little more beer while you wait. Of course, I did have to adjust my recipes to the new setup, but soon enough, my house beers tasted exactly how I wanted them.
Vive la Différence
My beer was good, but there was one surprise with split batches. While the beer seemed consistent enough from batch to batch, the two halves of a 10-gallon (38 l) batch could be noticeably different. It wasn’t a radical divergence, but the gravities might not be quite the same or the hops character could be slightly more pronounced. Side by side tasting revealed how inexact a science this is at the homebrew scale. There are just too many variables: one carboy might be a touch warmer, the yeast pitch rate is never quite the same, or the oxygen saturation might vary.