Daily cleaning keeps your BUNN running smoothly and tasting fresh
A BUNN commercial coffee maker needs cleaning every single day to prevent mineral buildup, stale coffee oils, and mold growth inside the brew basket and water lines. The daily routine takes about 10 minutes and requires only hot water and a damp cloth. Deeper cleaning—descaling the internal water lines—happens monthly and uses a commercial descaling solution mixed with water.
BUNN machines are built to handle high volume, but they fail faster when neglected. The brew basket clogs, the spray head sprays unevenly, and the water tastes like old coffee. This guide walks you through both the daily wipe-down and the monthly descale so your machine brews consistently and lasts years longer.
Key Takeaways
- Empty and rinse the brew basket when ready after each brew cycle, before coffee dries and hardens inside.
- Wipe the spray head with a damp cloth daily to remove dried coffee grounds that block water flow.
- Run a full descaling cycle monthly using a commercial descaling solution to clear mineral deposits from internal water lines.
- Never use vinegar on a BUNN—it can damage internal seals and void the warranty; use only BUNN-approved descaler or a commercial coffee machine descaler.
- Check the water level in the reservoir daily and refill with filtered water to reduce mineral buildup.
Empty and rinse the brew basket right after brewing
The brew basket is where grounds sit and water drips through. If you leave wet grounds in there, they dry hard and stick to the sides, blocking water flow on the next brew. Remove the brew basket as soon as the brew cycle finishes—usually within 30 seconds of the last drip.
Hold the basket over a trash can and tap it gently to knock out the spent grounds. Rinse it under hot running water, rubbing the inside with your fingers or a soft brush to remove all residue. Pay special attention to the seams and the underside where grounds hide. Shake off excess water and set it back in place, making sure it sits flat and centered.
If grounds have already dried and hardened, soak the basket in hot water for 5 to 10 minutes, then scrub with a soft brush. Never use a metal scrubber—it scratches the basket and can damage the spray head gasket.
Clean the spray head and dispersion plate daily
The spray head is the part that sprays hot water over the grounds. Coffee oils and mineral deposits build up on it and in the tiny holes, causing uneven water distribution and weak coffee. This takes only 2 minutes and should happen every day.
Let the machine cool for 1 to 2 minutes after the last brew. Dampen a clean cloth with hot water and wipe the entire spray head, paying attention to the flat bottom surface where the holes are. Use a soft brush or an old toothbrush to gently scrub around the holes if you see brown buildup. Do not poke into the holes with anything sharp—you can enlarge them and change how the machine brews.
If buildup is heavy, soak a cloth in hot water and hold it against the spray head for 30 seconds to soften the deposits, then wipe again. For stubborn mineral deposits, use a cloth dampened with a 50/50 mix of water and white vinegar on the exterior only—never let vinegar run into the machine's internal lines.
Wipe down the exterior and empty the drip tray
Coffee splashes, water drips, and dust collect on the outside of the machine. A quick wipe keeps it looking clean and prevents water from pooling where it can rust metal parts or damage electrical connections.
Use a damp cloth to wipe the top, sides, and front of the machine. Pay attention to the area around the brew basket and the water reservoir. Dry everything with a clean towel so water does not sit on the surface.
Empty the drip tray at least once a day, or more often if the machine is busy. A full tray can overflow and damage the machine or create a slip hazard. Rinse the tray with hot water and replace it.
Descale the internal water lines monthly
Minerals in water—calcium and magnesium—build up inside the heating element and water lines over time. This slows the brew cycle, makes the water hotter or cooler than it should be, and eventually clogs the machine. A monthly descale clears these deposits and takes about 30 minutes from start to finish.
You will need a commercial coffee machine descaler. BUNN sells its own brand, or you can use any descaler labeled safe for commercial coffee equipment. Do not use vinegar—BUNN specifically warns against it because it can corrode internal seals and damage the machine.
Fill the water reservoir with the descaling solution mixed at the ratio printed on the bottle (usually 1 part descaler to 3 or 4 parts water). Place a large empty container under the brew basket to catch the liquid. Turn on the brew cycle and let the solution run through for about 10 seconds, then turn it off. Wait 15 minutes to let the solution soak inside the lines. Turn the brew cycle back on and let it run completely. Repeat this soak-and-brew cycle two more times, then run two full cycles of plain filtered water to rinse out all descaler.
Check and refill the water reservoir with filtered water
The water you use directly affects how fast minerals build up. Tap water in many areas contains high levels of calcium and magnesium. Filtered water reduces this buildup and extends the time between descales.
Check the water level in the reservoir every morning before service starts. The reservoir should be full or nearly full. Use filtered water from a pitcher, a faucet filter, or a commercial water filtration system if your location has one. If your tap water is very hard (you can ask your water utility or buy a test strip), consider using bottled water or installing a point-of-use filter on the machine's water line.
Empty and rinse the reservoir itself once a week. Algae and sediment can grow inside if the water sits too long. Remove the reservoir, dump out any old water, scrub the inside with a soft brush, rinse thoroughly, and refill with fresh filtered water.
Troubleshoot slow brewing and uneven water spray
If the machine brews slower than usual or the water does not spray evenly over the grounds, mineral buildup is usually the cause. Start with a daily cleaning of the spray head as described above. If that does not fix it, run a descale cycle.
If the machine still brews slowly after descaling, the problem may be inside the heating element or water pump, which requires professional service. Contact BUNN customer support or a commercial coffee equipment technician. Do not try to disassemble the machine yourself—you can damage seals and void the warranty.
If one side of the brew basket gets more water than the other, the spray head may be tilted or the brew basket may not be sitting flat. Remove the basket, check that it is not cracked or warped, and make sure it clicks into place. Clean the spray head again and try a test brew.
Frequently Asked Questions
Can I use vinegar to descale a BUNN commercial coffee maker?
No. BUNN specifically advises against vinegar because it can corrode the internal seals and damage the heating element. Use only a commercial coffee machine descaler or BUNN's own descaling solution. Vinegar may void your warranty.
How often should I descale if I use filtered water?
Once a month is standard for most locations. If your water is very hard or you brew heavily every day, descale every two weeks. If your water is very soft or filtered, you may be able to stretch it to every six weeks. Watch for slower brewing as a sign that it is time to descale sooner.
What should I do if the spray head is clogged and will not spray?
Soak the spray head area with a damp cloth for 5 to 10 minutes to soften mineral deposits, then scrub gently with a soft brush. If that does not work, run a full descale cycle. If the spray head still does not work after descaling, it may need to be replaced—contact BUNN or a service technician.
Is it safe to run the machine while I am descaling it?
Yes, the descaling process requires you to run brew cycles with the solution in the water line. This is normal and safe. Just make sure you have a large container under the brew basket to catch the liquid, and do not let anyone try to brew coffee while you are in the middle of a descale cycle.
What happens if I do not clean the brew basket right away?
Coffee grounds dry and harden inside, blocking water flow on the next brew. This makes the coffee weak and uneven, and it can eventually clog the spray head. Always empty and rinse the basket when ready after each brew cycle.