Draft Line Cleaning: How Often, What to Use and Why It Matters

Draft LineCleaning

Draft lines need a caustic cleaning at least every two weeks (14 days) and an acid cleaning every three months, on top of the caustic, not instead of it. That is the Brewers Association standard, and it is the single best thing a bar can do for the beer it already paid for.

Beer leaves sugars, proteins, yeast and mineral scale behind in every line, and bacteria love that residue. Skip a cleaning and flavor goes first, then pour cost.

Caustic (sodium or potassium hydroxide) dissolves the organic film that beer leaves on tubing walls. Left alone, that film thickens into biofilm, which is very hard to remove and protects the bacteria living in it. The Brewers Association's retailer checklist treats a 7 to 14 day cycle as normal and says gaps over 21 days need special attention, which is a polite way of saying you now have a bigger job.

Strength and heat both matter. A 2% solution is the routine number. Older tubing or lines with a history of trouble get 3%. Keep the solution between 80°F and 110°F while it works. Colder solution cleans poorly, and some beer pumps can be damaged if the solution runs too hot, so check the equipment maker's limits.

There are two ways to get chemical into a line.

Recirculation uses an electric pump to push solution through the lines and back again for at least 15 minutes. The moving liquid scrubs as well as soaks, and the Brewers Association wants the cleaning flow rate to exceed the beer's normal pour rate. A Brewers Association best practices deck adds that flow rate should be 2 or more ounces per second and that flow direction can be alternated from one cleaning to the next.

Static cleaning pushes solution in with a pressure canister and lets it sit. It needs at least 20 minutes of contact time. The Brewers Association lists it as not recommended. If static is all you have, do not shave time off the soak.

Beer and hard water leave mineral deposits (beerstone) that caustic does not remove. An acid line cleaner, run quarterly and circulated for 15 minutes, takes care of it. Acid is an addition to the two week caustic routine. It never replaces one.

Lines are only part of the path. Parts that see air as well as beer are where mold and vinegar bacteria start.

• Faucets: disassemble and clean at every line cleaning, nitro faucets included.
• Couplers: hand clean at every two week cleaning, then fully disassemble and service every six months.
• FOBs (foam on beer detectors): clean every two weeks with the lines, fully disassemble and detail every six months.
• Tubing replacement: vinyl tubing should be under two years old and barrier tubing under ten. Vinyl jumper lines get replaced every one to two years.

Purge beer from the lines with water before the caustic goes in. After cleaning, flush with cool fresh water until the rinse water's pH matches your tap water. Only then repack the lines with beer. Caustic residue in a pint is a far worse problem than a dirty line.

Caustic and acid cleaners are hazardous. Wear eye protection and gloves, and follow the label and safety data sheet for the product you use.

• Vinegar or buttery aromas in the beer. The Brewers Association calls these signs of bacterial infection; butter or popcorn notes point to diacetyl, sour or vinegar notes to acetic bacteria.
• Tubing that looks cloudy or discolored.
• Haze in a FOB sight glass.
• Visible beer soil or mold on or inside faucets.
• Foamy or flat pours that do not trace back to temperature or gas pressure.

1. Shut off or disconnect the kegs and purge beer from the lines with water.
2. Remove faucets and soak and brush them, including nitro faucets.
3. Hand clean couplers (every two weeks) and FOBs.
4. Mix caustic to 2% (or 3% for older or problem lines) and bring it to 80°F to 110°F.
5. Recirculate for at least 15 minutes, or soak static for at least 20.
6. Every third month, follow with an acid cleaner circulated for 15 minutes.
7. Flush with cool fresh water until pH matches tap water.
8. Reassemble, check for leaks and missing O-rings, then repack with beer.
9. Fill in the cleaning log.

The Brewers Association asks for a visible cleaning log: date, who cleaned, which lines, chemical and strength, and what was disassembled. If a service company cleans your lines, ask for the same record and post it. A log protects you when someone asks why a beer tastes off. Clean lines pair with clean glass, so see beer clean glassware and how to pour draft beer for the rest of the job.

If you pour our beer and want help with draft quality or line questions, talk to our trade team.