Vinegar removes mineral buildup inside your Bunn without damaging the machine

Bunn coffee makers heat water constantly, which means minerals from tap water build up inside the tank and heating element over time. This buildup—called scale—slows down brewing, makes coffee taste off, and can eventually damage the machine. White vinegar dissolves this scale safely and costs just a few dollars. The process takes about 30 minutes of active work spread across a few hours, and you only need vinegar, water, and a container to catch the liquid.

Bunn recommends descaling every 30 days if you have hard water, or every 60 days with soft water. If you brew multiple pots daily, aim for the shorter interval. You'll know it's time when water brews slower than usual or coffee tastes bitter even with fresh grounds.

Key Takeaways

  • Mix equal parts white vinegar and water, then pour the solution into the top water reservoir of your Bunn.
  • Let the vinegar solution brew through the machine into a container below, then repeat the process a second time with fresh vinegar and water.
  • After both vinegar cycles, run two full tanks of plain water through the machine to rinse out all vinegar taste and smell.
  • The entire cleaning takes about two to three hours from start to finish, though most of that is waiting time between cycles.
  • Never use vinegar stronger than standard white vinegar (5% acidity), and never let vinegar sit in the machine overnight.

What you need before you start

Gather white vinegar (the standard 5% acidity kind sold in any grocery store), water, and a large container or measuring cup to catch the liquid that brews out. You do not need special descaling powder or commercial cleaners—vinegar works just as well and costs less. If your Bunn has a removable water filter cartridge, take it out before you start; vinegar can damage the filter media.

Make sure your machine is unplugged and has cooled for at least 15 minutes. Empty any water or coffee from the top reservoir and the carafe. If your Bunn has a spray head (the part that distributes water over the grounds), you can leave it in place—the vinegar will clean it as it brews.

The two-cycle vinegar cleaning process

Pour equal parts white vinegar and water into the top reservoir. For a standard Bunn, this is usually about 10 ounces of vinegar mixed with 10 ounces of water. Stir the mixture gently so it combines. Plug the machine back in and let it heat for about 5 to 10 minutes until you hear the heating element stop cycling (this means the water has reached temperature).

Place your container under the brew outlet and turn on the brew switch. The vinegar solution will flow through the machine slowly. Let it brew completely—this takes about 10 to 15 minutes. Once it stops, turn off the brew switch and let the machine sit for 15 minutes. This pause lets the vinegar soak into the heating element and internal pipes where scale builds up most.

After 15 minutes, repeat the entire process: pour another batch of equal parts vinegar and water into the reservoir, let it heat, and brew it through into your container. Two cycles are usually enough for light to moderate scale. If your machine has been neglected for months or you have very hard water, you can do a third cycle, but two is standard.

Rinsing out the vinegar completely

After the second vinegar cycle, empty the reservoir and refill it with plain water only. Brew the entire tank through the machine into your container. This is your first rinse cycle. Empty the carafe, refill the reservoir again with plain water, and brew a second time. Two full water cycles remove most vinegar taste and smell, but if you still detect vinegar when you brew a test pot of coffee, run a third water cycle.

The rinsing step is important because leftover vinegar will make your coffee taste sour and can leave a smell in the machine. If you notice vinegar taste in your first pot of coffee after cleaning, that is normal—brew and discard one more pot before making coffee you plan to drink.

Cleaning the carafe and spray head separately

While the vinegar is working inside the machine, clean the glass carafe by hand. Fill it halfway with equal parts vinegar and water, add a handful of uncooked rice or a bottle brush, and shake vigorously for 30 seconds. The rice or brush scrubs away coffee stains and mineral deposits on the inside walls. Rinse thoroughly with plain water.

If your Bunn has a removable spray head, soak it in a small cup of equal parts vinegar and water for 15 minutes while the machine is cleaning itself. Use an old toothbrush to scrub any mineral deposits from the holes, then rinse under running water. If the spray head is not removable, the vinegar solution brewing through the machine will clean it automatically.

What to do if scale buildup is severe

If your Bunn has not been cleaned in many months, the first vinegar cycle may brew very slowly or stop partway through. This means heavy scale is blocking the heating element. Do not force it—turn off the machine and let it sit for 30 minutes with the vinegar solution still in the reservoir. The vinegar will continue dissolving the scale even when the machine is off. After 30 minutes, plug it back in and try brewing again.

If the machine still will not brew after soaking, you may need to call a Bunn service center or a local appliance repair shop. Severe scale sometimes requires professional descaling equipment or internal disassembly. However, this is rare if you clean every 30 to 60 days as recommended.

How often to clean and what to do between cleanings

The frequency depends on your water hardness. If you have a water softener or use filtered water, descale every 60 days. If you have hard tap water (you can check this with an inexpensive test strip from a hardware store), descale every 30 days. If you brew more than six pots per day, move to the shorter interval regardless of water hardness.

Between vinegar cleanings, replace the water filter cartridge every 30 days if your Bunn has one. A clogged filter slows brewing and lets more minerals through. Empty and refill the reservoir every few days if the machine sits unused—stale water can develop odors. These small steps reduce the amount of scale that builds up and make your vinegar cleaning easier each time.

Frequently Asked Questions

Can I use apple cider vinegar or cleaning vinegar instead of white vinegar?

No. Apple cider vinegar is too weak and can leave residue. Cleaning vinegar (usually 10% acidity) is too strong and can damage seals inside the machine. Stick to standard white vinegar at 5% acidity, which is what Bunn recommends.

What if I leave vinegar in the machine overnight by accident?

Drain the reservoir and carafe when ready, then run plain water through the machine several times. Vinegar left sitting in the heating element for many hours can corrode internal parts. One night is usually not enough to cause permanent damage, but do not make it a habit.

Will vinegar smell linger in my coffee after cleaning?

A slight vinegar smell after the first pot is normal and goes away after you brew and discard one or two pots of coffee. If the smell persists after three water rinse cycles, run one more cycle and let the machine sit unplugged for an hour before brewing again.

Do I need to clean the inside of the water reservoir?

The vinegar solution flowing through the reservoir cleans it as it brews. If you see visible sludge or mold on the bottom, unplug the machine, empty the reservoir, and scrub the inside with a bottle brush and vinegar solution, then rinse thoroughly before reassembling.

Can I use vinegar if my Bunn has a built-in water filter?

Remove the filter cartridge before you start the vinegar cleaning. Vinegar can damage the filter media and reduce its effectiveness. Reinstall a fresh cartridge after you finish rinsing with plain water.