The Farmers' Cabinet, in Philadelphia, PA has a 26 tap beer bar. (Steve Legato/STEVE LEGATO)

You can brew only so much beer in a restaurant, and you can shoehorn only so many fermentation vessels among the tables and chairs and deep-fryers.

With thirst outpacing output, several regional brew pubs have been building, buying or renting off-site breweries to keep their own taps flowing and to supply an off-premises market of grocery stores, liquor marts, bars and restaurants.

Phil Bowers, owner of Brewer’s Alley, a 15-year-old brew pub in Frederick, just inaugurated a spinoff brewery about two miles up the road. The fledgling Monocacy Brewing occupies a former ice cream factory. “It could use some tender loving care, but it has everything a brewery needs,” including two walk-in freezers ideal for cold storage, Bowers says.

Brew master Tom Flores says Brewer’s Alley had maxed out at 800 to 900 barrels a year. The first order of business at Monocacy will be to fill demand at the brew pub for year-round labels such as Kolsch, IPA and 1634 Ale. That last is a throwback, incorporating rye, molasses and caraway: ingredients that would have been available to Maryland’s first colonists.

“Once we get ahead of demand, we’ll transition to a pilot brewery here at the pub,” says Flores, “experimenting with new raw materials.” He has been partnering with a farmer in Keymar, Md., in Carroll County, to grow and malt his own barley, and Flores seems anxious to convert his harvest of grain into beer. An English-style mild ale made from home-grown malt that’s on tap at Brewer’s Alley is unusually rich and full-bodied for its paltry 3 percent alcohol-by-volume content, he says.

Meanwhile, Monocacy Brewing will begin bottling and kegging Brewer’s Alley’s beers for distribution throughout Maryland and will also introduce its own brands, beginning with a rye IPA in early 2012.

A similar game plan is in effect at Devils Backbone Brewing in Roseland, Va., in Nelson County. After picking up nine medals in three years at the Great American Beer Festival, the brand will reach a wider audience after Dec. 1, when the owners fire up a 30-barrel brew kettle at a newly built brewery in Lexington, Va. The brewery had to be built 45 minutes away from the brew pub because Nelson County’s wastewater treatment system couldn’t handle the effluvia from the plant. Chief Operating Officer Hayes Humphreys says the new brewery will bottle and keg Vienna Lager, Eight Point IPA and 11 seasonal beers in 2012, shipping as far north as Manassas. The brew pub will act as “a research and development facility” for new recipes, he said.

Another satellite brewery has taken over the former Shenandoah Brewing in Alexandria. The facility opened in 1996 as a brew-on-premises, or BOP, a place where home-brewers could rent professional-grade equipment to make their own beer. Founder Anning Smith was about to shutter the business in June when a last-minute buyer emerged: a Center City Philadelphia restaurant called the Farmers’ Cabinet.

The Farmers’ Cabinet had intended to brew its own beer in a two-barrel nanobrewery, but it postponed those plans indefinitely when Shenandoah, with its five-barrel brew house, showed up in the for-sale ads.

Gone is the BOP. Since July, brewer Terry Hawbaker has been crafting a variety of Belgian-style farmhouse ales, including a fresh-hop saison flavored with newly picked Citra hops; Rauch-n-Roggen, made with rye malt smoked over cherry wood; and a rare example of a grisette, a low-alcohol (only 3.6 percent in this case), thirst-quenching Belgian table ale: “what the original saisons were meant to be,” Hawbaker says.

Alas, you can’t get them here. Hawbaker ships his entire output to the restaurant in Philly. “Right now, we’re just getting our feet wet,” says Farmers’ Cabinet co-owner Matt Scheller. But sometime over the next few months, he promises, the Farmers’ Cabinet Brewhouse (as the operation is being renamed) will open a tasting room offering growler fills and a light snack-and-sandwich menu. Scheller anticipates selling the beers in 750-milliliter bottles.

Off-premises is “a different market, no doubt,” says Bowers of Brewer’s Alley. You need to persuade a distributor to carry your beers, then entrust them to retailers who might plop them among dozens (perhaps hundreds) of rival brands. Bowers was cautious: Before sinking thousands into a production brewery, he was able to gauge demand by contract-brewing the six-pack version of several of his brands at the Flying Dog Brewery across town. He found a ready market, selling 4,000 to 5,000 cases per year.

The enticements outweigh the risks. For the first half of 2011, craft beer volume grew by 14 percent nationwide, and sales soared 15 percent higher than in 2010.

There are singular successes, such as Oskar Blues in Lyons, Colo. Nine years ago, it was an average-size brew pub in this Rocky Mountain gateway town of 1,600. Then owner Dale Katechis began canning his Dale’s Pale Ale with a manually operated canner capable of filling two cans at a time. Other U.S. craft breweries had contract-brewed canned beers (mostly amber lagers and golden ales) at bigger breweries, but Oskar Blues was the first to operate its own canner and the first to can an aggressively hopped pale ale.

Today, Oskar Blues operates an off-site plant in nearby Longmont, Colo., which is on pace this year to turn out 58,000 barrels’ worth for shipping to 26 states. In December, the company will take possession of a new canning line able to fill 300 cylinders a minute. That machinery will enable Oskar Blues to begin filling 16-ounce cans with a new brand called Deviant Dale’s IPA, an 8 percent alcohol powerhouse seasoned with pungent Columbus hops.

“It’s been a wild ride,” says Chad Melis, marketing director for Oskar Blues.

And it probably has a lot of pub brewers stroking their chins and going, “Hmmm.”

Bill Madden, founder of the Mad Fox brew pub in Falls Church, was pouring beer at the Taste of DC last week when I asked him whether he had thought of opening a packaging brewery.

“We’re talking about it,” he said. “We’re considering our options.”