Think Twice Before Drinking Draft Beer

Bars often fail to maintain clean beer lines. Here's what that means for your pint.

Few things hit the spot like a cold pint of draft beer. That's because beer on tap, when done right, has a cleaner, smoother, fresher taste than its bottled or canned counterparts. However, the quality of draft beer can depend heavily on which bars you frequent, because dirty lines carrying the beer between the keg and the tap can ruin even the best brews. You've likely experienced this beer gone wrong: It tastes flat, acidic, and otherwise unpleasant. And dirty beer systems don't just put the beer at risk, but the customer's health, too.

At Walt's Bar in Eagle Rock, Los Angeles, the beer lines are cleaned weekly. That's because owners Jeff and Julia Johnsen understand the importance of an immaculate beer system.

"I've worked in bars my whole life—so has my dad," says Jeff Johnsen. "Draft beer lines need cleaned and changed super regularly. That's something I saw a lot of: nasty draft beer systems that weren't well taken care of."

Eric Huwig designed the direct draw beer system for Walt's Bar. "Direct draw" means that the kegs sit directly underneath the beer taps, instead of traveling through fifty feet of tubing to get to the draft faucet. "It literally comes right out of the keg," says Johnsen. "Only a three foot tube. I like that better. Because you don't have beer that's been sitting in lines and losing carbonation."

Johnsen points out that very few bars can operate this way. With limited storage space, an overabundance of taps, and poor bar design, most bars are a tangled mess of lengthly beer lines. And as he says, these lines don't just serve as a conduit for the beer as it's being poured—it holds the beer long after that, too. Your beer literally sits there in the tubes, sometimes for hours. Some lines, Johnsen says, are long enough to have a capacity of three or four pints, and if the beer isn't being sold fast enough, it remains stagnant. This results in less than perfect draft beer, and bacteria can start to grow inside the tubes.

"If I showed you some pics of the draft lines that Eric sends me," Johnsen says. "Dude, stick with a bottle or can, unless you know that shit's being serviced."

Well, hearing that ruined by affinity for a plate of dolmas and a cold 24-oz. Yuengling on tap back home. Shit.

Walt's Bar, which also provides the spectacular combination of hot dogs and natural wine, is a champion of local Southern California beers. Each one drawn from the tap tastes crisp, fresh, and aromatic, and Johnsen's and Huwig's respect for clean beer lines makes it possible. Maintenance, system care, and a fine attention to detail are what make Walt's stand head and shoulders above other bars in Los Angeles. You can taste the difference.

How dirty beer lines affect draft beer

Most beer drinkers are likely to detect an unkempt beer line, even if they don't know that's why their beer tastes off. Dirty lines do in fact spoil a beer's flavor, and it's a huge problem. A 2021 study titled "Microbial Communities in Retail Draft Beers and the Biofilms They Produce" had this to say:


We found that retail draft line contamination is rampant and that routine line cleaning methods are insufficient to efficiently suppress beer spoilage. Thus, many customers unknowingly consume spoiled versions of the beers they consume. This study identified the bacteria and yeast that were resident in retail draft beer samples and also investigated their abilities to colonize tubing material as members of biofilm communities.

Spoiled beer is the result of bacteria, and it can creates a more acidic and vinegar-like taste. If you've ever said to yourself, "Boy, this beer tastes like piss," there's a reason for that, and it's dirty beer lines. Unless, of course, that beer is supposed to taste like piss. (Looking at you, Miller High Life.)


Aroma can also be diluted by dirty lines as well. Beer should smell good; whether it's malty, hoppy, smoky, or nutty, there should be a pleasant fragrance emanating from your draft beer. If it's completely gone, well, you might want to find a new watering hole.

There are health benefits to clean beer lines, too: Johnsen says that "We'll all wake up with a more manageable hangover."

"Drinking weird shit growing on the inside of these lines—sugar, yeast—it's no good," he says. Contaminated beer lines build up bacteria, which have the potential to lead to diarrhea, headaches, and nausea. Though getting sick from bad beer isn't all that common, it's frustratingly simple to prevent bad beer in the first place.

The most common bacteria to infect beer lines are Pediococcus and Lactobacillus, but also Obesumbacterium, Pectinatus, and Zymomonas. When lines aren't clean, mold and mildew collect, turning them brown or black and encouraging growth. Plus, most beer lines are made of vinyl tubes, and because these tubes don't have a perfectly smooth interior surface, bacteria can cling and accumulate easily. Diacetyl, a chemical found in beer which gives it its aroma, also has a tendency to accrue in beer lines rife with Pediococcus and Lactobacillus, creating a slick, slimy texture within the tubes.


How to drink beer in bars without getting sick

Admittedly, this isn't the main bacterial issue in bars—Johnsen acknowledged the importance of clean glassware above all. He even offers this tip to know if your pint glass is contaminated: "If you ever go to a bar and get a beer, you should not see any bubbles on the side of the glass. That means there's some sort of contaminant on there. The yeast latches on to that food or that contaminant, creating the bubbles."


Enjoying a draft beer is a simple, romantic, affordable luxury, but far too often, it's being robbed of its joy by improper maintenance. Knowing all of this, the harrowing words of a passionate and battle-tested bar owner continue to ring true: "Stick with a bottle." It is, ironically, a sobering thought.

More bars should be cleaning their beer lines, and more bars should be embarrassed that they don't. Sure, it's a pain in the ass, requiring a lot of disassembling, soaking, flushing, cleaning, and reassembling. Kegworks and the Brewers Association both recommend cleaning beer lines at least every two weeks; others believe it should be done weekly. Regardless, for the sake of draft beer enjoyers everywhere, it needs to get done. Until then, I'll stick with Walt's.