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Crowlers, 32 oz aluminum cans filled and seamed on-demand at a brewery taproom, solved a problem that growlers never quite managed: how to give customers fresh draft beer to go in a package that stays fresh. The traditional 64 oz glass growler is convenient for the brewery and the consumer, but it’s notoriously unreliable for maintaining beer quality beyond a day or two after filling because it can’t be purged of oxygen as effectively as a sealed can. I’ve watched dozens of brewery taprooms switch from growlers to crowlers and the quality difference in the beer customers take home is significant. For homebrewers, understanding crowler technology is useful if you’re building out any kind of on-premise serving setup.
How crowlers work
A crowler is a standard 32 oz (946 mL) aluminum beverage can with a straight-walled opening (unlike a regular beverage can’s neck) that allows filling with a draft faucet. The filling process: the empty can is pre-purged with CO2 to displace atmospheric oxygen; beer is counter-pressure filled from the draft tap into the can; a cardboard lid is placed on top; the can is seamed on a manual or automatic seaming machine. The seam is a standard double-seam crimp, the same type used on commercial canned beverages. Once sealed, a properly filled crowler is essentially a single-use sealed can with the same oxygen barrier properties as any commercial canned product.
Crowler seaming equipment
The seaming machine is the key piece of crowler equipment. Options:
- Wild Goose Canning Crowler Can Seamer: The most commonly used taproom seamer, manual crank operation, consistent seam quality, approximately $2,500–3,500. Widely used in US craft taprooms.
- Oktober Can Seamer: Another popular option with a lever-operated mechanism, approximately $1,800–2,500. Slightly lower throughput than the Wild Goose but suitable for lower-volume taproom use.
- Pneumatic seamers: Higher-throughput pneumatic models ($4,000–8,000) for busier operations that are selling large numbers of crowlers daily.
Crowler vs. growler quality comparison
- Crowler oxygen exposure: A properly purged and seamed crowler achieves dissolved oxygen levels of 50–150 ppb at fill, comparable to professionally canned beer. Beer remains fresh for 2–4 weeks if refrigerated.
- Growler oxygen exposure: Even with a CO2 purge before filling, a 64 oz growler filled at a tap typically achieves 400–800 ppb dissolved oxygen, 4–8x worse than a crowler. Shelf life: 1–3 days at optimal; often tastes noticeably oxidized after 48 hours.
- Light exposure: Aluminum crowler is completely opaque, zero light exposure. Clear or tinted glass growlers allow UV light to skunk hop-forward beers within hours.
- Practical winner: Crowler is objectively superior for beer quality. The tradeoff is the seaming equipment capital cost and the recurring cost of cans ($0.60–0.90 each).
Carbonation management during filling
Proper fill technique minimizes foaming and maintains carbonation. Best practice: tilt the can 45° and fill slowly against the can wall (same as pouring a glass of beer) to minimize turbulence. Allow any foam to settle in the can before placing the lid, then seam immediately. Beers with very high carbonation (Belgian styles, highly carbonated wheat beers) are more challenging to fill without excessive foaming, these may benefit from cooling the can in an ice bath before filling. Highly dry-hopped beers (hazy IPAs) can foam aggressively from the nucleation sites created by hop particles; chill the keg to near-freezing before crowler filling sessions to reduce foaming.
Common Questions
Are crowlers legal for homebrewers to use?
In the US, homebrewing for personal consumption is federally legal (since 1978), but selling homebrew is not, the crowler equipment question for homebrewers is about packaging for personal sharing and transport, not commercial sale. There’s no regulatory restriction on a homebrewer seaming crowlers of their own beer for personal use or for sharing at homebrew club events. The practical barrier for homebrewers is the cost of a seaming machine ($1,800+) relative to the use case, most homebrewers find growlers or simply bottling with a bench capper more economical for sharing homebrew. Homebrew clubs sometimes share a crowler seamer among members for events. If you’re building out a more serious home draft system with multiple taps and want to enable to-go options for homebrew competitions or club swaps, a crowler seamer is a genuinely useful addition.
