For those unfamiliar with the term, a “growler” is a large vessel that certain brewpubs and package stores will fill with draft beer and sell to Aleheads as a “take-out” option. These environmentally-friendly containers can generally be purchased and then refilled for very reasonable prices (or returned empty for a deposit refund). While they vary in size, the industry standard is a 64-ounce (half gallon) glass jug with a screw-on top. Here in ‘Bama, one of my local package stores sells plastic milk jugs which serve as their versions of growlers. Classy.
The growler was so named for the growl-like sonic emanations created when CO2 seeped out of the top of the galvanized pails which were used in the days before the development of the modern growler. Just like today’s versions, these pails were lugged by ancient Aleheads to slog their suds home from the local taphouse. Of course, our forerunners had to drink their growlers almost immediately. Today, thanks to modern refrigeration and sterilization procedures, a properly sealed growler can be stored for a long time without spoiling.
And that brings us back to Sir Magnus’s question. Unopened, a growler can sit in your fridge for quite awhile, but just because the beer won’t spoil doesn’t mean that it will taste fresh indefinitely. It is HIGHLY recommended that you consume the growler on the day you purchase it. I wouldn’t wait any longer than that since that “fresh from the tap” flavor will fade fairly rapidly. And while your beer may still be drinkable after a few days, it won’t be anywhere near as good as it was when it was first poured. Of course, once it’s opened, you should consider the growler to be nothing more than a large beer bottle (which, you know, it is). You wouldn’t put an open 12-ounce bottle back in the fridge and expect it to taste good the next day. Same is true for a growler…so once you crack that sucker open, finish it!
In truth, if you don’t plan on drinking your growler that day, you’re better off buying bottles or cans which will stay fresher for MUCH longer than a tap-poured growler. Growlers are the take-out containers of the beer world. You don’t get pizza delivered to your house to eat a week later. And you don’t buy a growler unless you plan on drinking it ASAP. But yes, if life gets in the way and you don’t get around to consuming your growler for a day or two, it will be fine. Maybe not quite as fresh or effervescent as it was when you first bought it, but it will be close enough. Beyond a few days though and you’re starting to enter the world of the “drain pour”. And that, my friends, is enough to make a grown man cry.