A keg washing machine is a device that cleans and sanitizes the inside of beer kegs, using a spray ball or rotating jet to blast cleaning and sanitizing solutions through the keg’s spear. This guide walks you through the complete process—from rinsing to sanitizing—so you can keep your kegs in top condition, whether you’re a homebrewer or a small brewery.
Ingredients
- 1 empty beer keg (5 gallons / 19 L, with spear removed)
- 5 gallons (19 L) warm water (for initial rinse)
- 1/2 cup (120 ml) caustic soda (sodium hydroxide) or 1 cup (240 ml) PBW (Powdered Brewery Wash)
- 5 gallons (19 L) hot water (160°F / 71°C) for cleaning solution
- 1/2 cup (120 ml) food-grade acid (e.g., phosphoric acid) or 1/4 cup (60 ml) peracetic acid (for sanitizing)
- 5 gallons (19 L) cold water (for final rinse)
- Food-grade lubricant (for spear O-rings)
- Protective gear: rubber gloves, safety goggles, apron
Instructions
- Prepare the keg: Remove the keg spear using a spear wrench, following the manufacturer’s instructions. Rinse the keg with warm water to remove any residual beer or debris. Discard the rinse water.
- Set up the washing machine: Place the keg upside down on the washing machine’s spray ball or connect the keg to the machine’s coupler, depending on your model. Ensure the keg is securely fastened.
- Run the caustic wash cycle: Fill the machine’s reservoir with 5 gallons (19 L) of hot water (160°F / 71°C) and add 1/2 cup (120 ml) caustic soda or 1 cup (240 ml) PBW. Run the cycle for 15 minutes, allowing the solution to circulate through the keg and spray ball. This removes organic residue (beer stone, yeast).
- Rinse with hot water: Drain the caustic solution and rinse the keg with hot water (160°F / 71°C) for 5 minutes to remove all cleaning chemicals.
- Rinse with cold water: Run a cold water rinse for 5 minutes to cool the keg and flush any remaining residue.
- Sanitize the keg: Prepare a sanitizing solution according to the manufacturer’s instructions (e.g., 1/2 cup / 120 ml of food-grade acid per 5 gallons / 19 L of water, or a peracetic acid solution at the recommended concentration). Run the sanitizing cycle for 10 minutes.
- Final rinse (if required): Some sanitizers require a final rinse with sterile or cold water. If using a no-rinse sanitizer, skip this step. If rinsing, use cold water for 5 minutes.
- Drain and air dry: Remove the keg from the machine and let it air dry upside down on a clean surface. Do not wipe the inside with a cloth, as this can reintroduce bacteria.
- Reassemble the spear: Once dry, apply a thin layer of food-grade lubricant to the O-rings and reinsert the spear. Pressurize the keg with CO2 to check for leaks before filling.
Tips
- Substitutions: If you don’t have caustic soda, use PBW or a similar alkaline cleaner. For a no-rinse sanitizer, use peracetic acid at 100–200 ppm, but follow the label instructions.
- Safety first: Always wear rubber gloves and safety goggles when handling caustic soda or acid. Add chemicals to water, not the other way around, to avoid splashing.
- Common mistake: Skipping the hot water rinse after caustic can leave residue that affects beer flavor. Always rinse thoroughly.
- Regular maintenance: Clean kegs immediately after emptying to prevent beer stone buildup. If you notice a film, repeat the caustic cycle.
Serving Suggestions
Once your keg is clean and sanitized, fill it with your favorite homebrew or commercial beer. Serve at the appropriate temperature for the style—ales at 50–55°F (10–13°C), lagers at 40–45°F (4–7°C). Use a clean CO2 line and coupler to maintain carbonation and freshness.
Variations
- Manual cleaning: If you don’t have a keg washer, you can clean the keg manually using a keg brush and the same cleaning solutions, but it’s more labor-intensive.
- High-pressure cycle: Some machines have a high-pressure setting for heavily soiled kegs; run an extra 5 minutes on that setting.
- Acid wash: For beer stone (calcium oxalate), use a dedicated acid wash (e.g., phosphoric acid) after the caustic cycle, then rinse thoroughly.
Storage and Reheating
Clean and sanitized kegs should be stored with the spear in place and pressurized with a small amount of CO2 (5–10 psi) to keep seals intact. Store in a cool, dry place. If you don’t plan to use the keg within 2 weeks, re-sanitize it before filling—don’t rely on the previous sanitization. Do not store kegs with liquid inside; always empty and clean them.
Frequently Asked Questions
Can I use bleach to clean my keg? Yes, but bleach can leave a chlorine flavor and is not as effective as caustic or PBW. If you use bleach, use a very dilute solution (1 tbsp per gallon) and rinse extremely well with hot water.
How often should I clean my keg? Clean after every emptying, especially if it held beer. Beer residue can harbor bacteria and cause off-flavors.
Do I need to remove the spear every time? Yes, for thorough cleaning. The spear has hard-to-reach areas where residue can hide. Removing it also allows you to inspect and replace O-rings.
What temperature should the cleaning solution be? Hot water (160°F / 71°C) is ideal for caustic cleaners—it dissolves organic matter more effectively. Do not use boiling water, as it can damage seals.
Can I use the same sanitizer for kegs as for bottles? Yes, but ensure it’s food-grade and safe for stainless steel. Star San (acid-based) is a popular choice.
How do I know if my keg is truly clean? After rinsing, the inside should be spotless with no visible film. You can also check the pH of the final rinse water—it should be neutral (around 7).
Related
- Dulce Brioche Bread: Sweet Mexican Brioche Recipe
- Euro Classic Brioche Recipe: Rich & Buttery
- Frozen Brioche Bread: How to Freeze, Thaw & Reheat
More recipes to cook
Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes
Spotted an error? Tell us and we will correct it (corrections policy).