Biofilm is the main reason draft lines need regular cleaning. It's a slimy layer of bacteria and wild yeast stuck to the inside of the tubing. It sits inside the tubing where you can't see it, and it changes how the beer tastes.
How It Forms
Beer leaves a thin coat of sugar and protein on the tubing wall. Bacteria settle on that coat and start feeding. As they grow, they make a sticky goo that holds them to the wall and shields them. That goo plus the bugs living in it is biofilm.
The protective layer is the problem. A quick rinse slides right over it. Weak cleaner only reaches the top. The bugs underneath survive and grow back fast.
What's Living in It
The Brewers Association Draught Beer Quality Manual lists the common ones: Lactobacillus, Pediococcus, Pectinatus, and Acetobacter. Each one leaves its own mark on the beer:
- Acetobacter turns alcohol into acetic acid. That's the vinegar taste.
- Lactobacillus and Pediococcus make lactic acid and diacetyl. You get sour notes and a buttery or butterscotch flavor.
- Wild yeast can show up in lines with a spotty cleaning history. It brings musty or barnyard flavors.
The Brewers Association notes these organisms are not a health risk. Our post on off-tastes in draft beer helps you match a flavor to its cause.
What Removes It
Getting biofilm out takes the right chemical at the right strength, left in long enough, with the solution moving. The Brewers Association spells it out:
- Caustic line cleaner mixed to 2% for routine cleaning, 3% for dirty lines
- Solution warmed to 80 to 110°F
- Pumped through the lines for at least 15 minutes, at up to 2 gallons per minute
The pump makes a big difference. Moving solution scrubs the tubing wall. Solution sitting still in the line has to do all the work with chemistry alone.
Cut any of those corners and some biofilm stays. It grows back faster because the bottom layer was never removed.
Check the Faucets and Couplers
Biofilm grows anywhere beer touches. Faucets are one of the worst spots because they get beer and air every time someone pulls a pint. Couplers and shanks collect it too. Pumping cleaner through the line doesn't reach every surface inside those parts. They have to come apart and get scrubbed by hand at each cleaning.
Beer Stone Makes It Worse
Beer stone is a hard mineral crust that builds up in lines over time. Caustic cleaner leaves it in place. Its rough surface gives biofilm a place to hide. An acid cleaning every quarter keeps it under control. See what beer stone is.
Stay on Schedule
The longer biofilm grows, the thicker it gets and the harder it is to strip. That's why the Brewers Association and Pennsylvania law both set a 14-day limit. Our post on the two-week cleaning schedule explains more.
We clean with a Micro Matic recirculating pump at full strength, and we take every faucet and coupler apart. Call (267) 282-1002 to set up a visit.