What is a Growler? and other growler questions answered

In the past I’ve written about laws concerning growler fills, how to clean your growler and I’ve even reviewed a stainless steel growler but I haven’t spent any time explaining “what is a growler?” and some of the basics surrounding them.

Growler: A reusable vessel that’s purpose is to transport beer (possibly cider, Kombucha) from keg to home. In Maine these are 32 or 64oz glass bottles or could be stainless steel depending on the brewery.OX Growler

The Name: I’ve heard two origin stories, the most common is that in the late 1800’s beer to go was transported from the saloon to home via an enamel pail with lid, the carbonation released by the sloshing beer made “Growling” sounds as it escaped the lid. The other story is that the “Growler” was actually the person complaining that the bartender hadn’t filled the pail enough causing them to growl. You may come across some other odd names out there like “Howler” or “Bangor Bottle” some breweries have given their 32oz growlers a different name to differentiate them from the standard 64oz bottle..

The Caps: there are two kinds, metal and plastic. The metal cap is thin and cheap with a paper or plastisol seal and should be thrown away after use. The plastic cap are better and can be reused, these should be washed and stored separately so that moisture isn’t sealed into the growler promoting mold or mildew growth. If you decide to reuse a plastic cap make sure to inspect it for cracks, if they are bumped they can break.

Metal and Plastic growler caps.

Metal and Plastic growler caps.

The growler is a wonderful thing, brewery fresh beer that you can pick up and take home for the price of a fill plus deposit. Clean the glass and bring it back for a fill anytime you are near the brewery. It’s pretty easy. Below are some of the common questions I face, I could answer all of them but I decided to reach out to the experts and let them answer.



I’m purchasing a growler to take to a friend out of state, do I need to keep my growler on ice or can it warm up?

“It’s always best to keep a growler cold and drink it as soon as possible. Growlers filled from the tap are a great way to get fresh beer, but ensuring it stays fresh and carbonated is very important. Definitely keep any growlers that you are traveling with on ice in a cooler and refrigerate upon arrival. If the growler warms up too much, some of the CO2 will come out of solution and you will have flat beer. If you hear a loud hiss when you open the cap, that’s a sign that you have lost some of the carbonation in the beer. So, keep it cold, drink it soon and refill often!” Tim Bissell, Gneiss Brewing Company

I love your beer but I never remember to bring back my growler and now I have five of them in the closet, will you take them all back?

“It’s a common problem to forget to have your growler with you when you want to stop by your favorite brewery for a fill-up. Some people have begun making wooden milk-crate style boxes (like the super-stylish Allagash House Beer crate), so that they can safely keep a growler from each of their local favorites safely in their trunk without them rolling around and breaking, which is the most common deterrent to keeping them in your car.

If you do accumulate more growlers than you need, and you want to return them, it is our [Foundation Brewing] practice to accept them for a return on the deposit *IF* they have been well cared for — meaning they are clean and free of damage. We need to be able to sanitize them and pass them on to a new customer. If we don’t feel we can do that, we will not return the deposit. This is not the policy of every brewery, so before you buy 6 growlers from a brewery, ask them if you can return the extras you have at home.” Joel Mahaffey, Foundation Brewing Company

I have a growler from another brewery and I don’t want to buy a second growler, will you fill the one I have with me?

“Maine law is pretty strict about growler labeling. Under Maine law, brewers can only fill growlers that are properly labeled with all the elements required under federal and state law for a bottle, including our brewery name and location, surgeon general’s warning etc. As a result, most Maine brewers will only fill our own branded growlers.” Heather Sanborn, Rising Tide Brewing Company

I bought a 64oz growler and can’t finish it all in one sitting, can I reseal and finish my growler another day or do I have to finish it now?

“I receive some form of this question very frequently! While we as craft beer junkies love our beer, there are certainly times (many in fact) where four full pints of our favorite brew is too much for one sitting. The simplest answer I can provide is to place the growler on an even par with a two liter bottle of soda. Once opened, carbonation levels will drop – especially when warm. Most everyone has the experience tucked in their memory of pouring the overly sweet, flat, non-refreshing cup of soda at the end of a day of backyard shenanigans. There is nothing “wrong” with that cup of soda, but certainly not much right about it either. If kept cold, however, and with the cap on (when not being poured), a growler will last relatively well, just like that bottle of soda. Carbonation will impact the presence of hop aroma, the level to which the malt sweetness lingers in the mouth, and the overall pleasure of the experience.

All of this assumes a few things

First, sanitation, sanitation, sanitation. We spend most of our time in the brewery washing and sanitizing all of our equipment – including growlers. We do not refill glassware that is returned to us until it has been properly cleaned and sanitized by us. Any bacteria in that vessel will begin to spoil your beer almost immediately. If your growler is not properly clean, your beer will begin to spoil immediately. Not only should you not leave some for later, you should never drink beer that has been run through dirty lines and/or into dirty growlers.

Second, proper CO2 purging. Before filling our growlers, we purge the glassware of all air, leaving the vessel full with CO2. Beer spoiling bacteria cannot grow in an anaerobic atmosphere (a place with no oxygen). Also, as beer makes contact with oxygen, it will quickly begin to oxidize. Oxidized beer will take on many “off-flavors” including “wet cardboard.”  Once opened, this process will begin, however, beer coming from a CO2 rich environment will take longer to take in these flavors than one which contained oxygen from the beginning.

Third, filtered or stable beer. Any beer that contains live yeast (most beers that have not been pasteurized contains some – “unfiltered” or “bottle conditioned” products contain lots) still holds the potential for further fermentation among other things. Unfiltered beer needs to be treated with care. Temperature is of critical importance. For an ale, keeping the product in refrigeration should keep the yeast dormant and the product stable. A growler that is open and allowed to come to room temperature will allow oxygen in, release dissolved and free CO2 from the solution and encourage the yeast to reactivate and change your beer – potentially quite drastically – in a short period of time.

So… What to do? Many breweries now have multiple sizes of growlers. The state recognizes a growler as a “vessel between 32oz and 64oz” so keep your options open. So, when you are not in a place to finish a full 64oz growler you can look for another size, look for more friends, or understand that within a couple days of opening a well packaged and purged growler you will begin to lose carbonation and open up the door for oxidation to take hold. If you are not purchasing a well purged, properly packaged growler… Well… Just don’t.” Andrew Geaghan, Geaghan Brothers Brewing

How long can i keep a growler that I’ve just had filled if the seal isn’t broken?

“We recommend consuming as quickly as possible. As long as they are filled correctly, cap is kept tight and growler is kept cold, then a few days to a week is no problem.  We have seen them last as long 2 weeks though, with no ill effects.  I’m not sure who has the will power to wait longer than that so we haven’t bothered to test beyond the 2 week mark.” Jake Austin, Austin Street Brewing

I’m about to bottle a batch of homebrew, can I fill up my growlers to bottle condition the beer?

“To paraphrase Chris Rock, “You can drive a car with your feet if you want to, but that doesn’t make it right.” You CAN do it, and some homebrewers do, but the results are wildly inconsistent and less-than perfect. We don’t recommend bottling homebrew into growlers for two reasons. First of all, growlers aren’t meant to hold carbonation for as long as crimped bottle caps, and so it’s very possible that by the time you get around to opening the beer, it will be flat. The second reason is that a half or full gallon of beer will produce a LOT of yeast sediment at the bottom of the growler when it is conditioning. When you go to pour your beer, the thick layer of sediment will be disturbed and will cloud up the beer (and make it taste not so great). In homebrewing, growlers are really meant as a way to transport beer from your keg. When bottling, stick to beer bottles!” Zeth Lundy, Central Street Farmhouse


If you have a question about growlers that isn’t covered in this post or one of my previous posts, comment below and I’ll get an answer for you.


64oz Growler from Lively Brewing

64oz Growler from Lively Brewing

Chad Lothian

About Chad Lothian

Chad Lothian lives in Old Town, Maine. He is a craft beer enthusiast and homebrewer. Chad has travelled to brewpubs, breweries and brewfests all over New England.