Empty and rinse the reservoir weekly to prevent mineral buildup

The BUNN reservoir — the tank that holds water before it brews — collects mineral deposits and sediment over time, especially if you have hard water. Cleaning it weekly takes about five minutes and keeps your coffee tasting fresh. Start by unplugging the machine and letting it cool for at least 30 minutes.

Lift the reservoir straight up and away from the machine. Empty any remaining water into a sink. Rinse the inside under warm running water, using your hand or a soft cloth to wipe the bottom and sides. Do not use a brush with stiff bristles — BUNN reservoirs are plastic and scratch easily. Rinse until the water runs clear, then set the reservoir aside to air-dry before refilling.

Key Takeaways

  • Empty and rinse your BUNN reservoir every week to stop mineral deposits from building up inside the tank.
  • Use only warm water and a soft cloth for weekly cleaning — never use vinegar or descaling solutions on the reservoir itself.
  • For heavy mineral buildup inside the machine's internal lines, run a full descaling cycle using BUNN's official descaling solution or white vinegar through the brew basket.
  • Replace the reservoir if you see cracks, cloudiness that won't rinse away, or a smell that persists after cleaning.

Deep clean the reservoir with vinegar for stubborn mineral deposits

If your reservoir has white, chalky buildup on the inside that rinsing does not remove, soak it in a vinegar solution. Fill the reservoir halfway with equal parts white vinegar and warm water. Let it sit for 30 minutes to an hour, then scrub gently with a soft cloth or non-abrasive sponge. Rinse thoroughly under running water at least three times to remove all vinegar smell.

Do not leave vinegar in the reservoir longer than one hour — prolonged contact can damage the plastic seals. After soaking, inspect the inside for any remaining white spots. If buildup persists, repeat the soak for another 30 minutes. Once clean, rinse again and let the reservoir air-dry completely before reinstalling it on the machine.

Run a descaling cycle through the brew basket for internal lines

Mineral buildup inside the machine's heating element and brew lines requires a different approach than cleaning the reservoir itself. Fill the empty reservoir with BUNN's official descaling solution (follow the package ratio) or use a 1:1 mix of white vinegar and water. Do not add coffee grounds or a filter.

Place an empty carafe under the brew basket and run the machine as if you were brewing coffee. Let the solution flow through completely. Repeat this cycle two more times with fresh solution. After three cycles, empty the reservoir and fill it with fresh water only. Run two full brew cycles with water alone to rinse out any remaining vinegar or descaling solution. This process takes about 20 to 30 minutes total.

Check the water line and spout for clogs

If water drips slowly or unevenly from the brew basket, the spout or internal water line may be partially blocked. Unplug the machine and let it cool. Look at the small opening where water exits the brew basket — you may see white mineral deposits around the edge.

Soak a paper towel in white vinegar and hold it against the spout opening for two to three minutes. This softens mineral deposits without requiring you to disassemble the machine. If the drip does not improve, fill the reservoir with vinegar solution and run one brew cycle without a filter or carafe underneath — let the vinegar flow through the spout into a sink. Repeat with plain water twice to rinse. If water still does not flow normally, the internal heating element may need professional cleaning.

Dry and store the reservoir correctly

After cleaning, always air-dry the reservoir completely before putting it back on the machine. Moisture left inside can promote mold growth or cause electrical issues. Stand the reservoir upside down on a clean towel for at least one hour, or place it right-side up in a warm, dry spot for 30 minutes.

Before reinstalling, wipe the bottom and sides with a dry cloth to remove any water droplets. Check the rubber gasket (the seal where the reservoir connects to the machine) for cracks or hardening. If it looks damaged, the reservoir may leak. Slide the reservoir straight down onto the machine until it clicks or seats firmly — you should hear or feel a slight resistance.

Know when to replace the reservoir

BUNN reservoirs last several years with regular cleaning, but they do wear out. Replace the reservoir if you see cracks, permanent cloudiness inside that vinegar soaking does not clear, a persistent smell even after thorough cleaning, or water leaking from the seams. Cracks can allow water to drip onto the heating element and damage the machine.

You can order replacement reservoirs directly from BUNN or through major kitchen equipment retailers. Measure your current reservoir or note your BUNN model number before ordering — reservoir sizes vary. Installation is straightforward: empty the old one, lift it away, and slide the new one on until it seats.

Prevent mineral buildup with filtered water

The easiest way to keep your reservoir clean is to fill it with filtered water instead of tap water. Filtered water has fewer minerals, so deposits build up much more slowly. If you use tap water, empty and rinse the reservoir every seven days rather than waiting until you see buildup.

In areas with very hard water, consider running a descaling cycle once a month instead of waiting for visible mineral deposits. This prevents the buildup from getting thick enough to slow water flow or affect taste. Keep a bottle of BUNN descaling solution or white vinegar on hand so you can descale without having to shop for it when you notice the machine is running slowly.

Frequently Asked Questions

Can I put the BUNN reservoir in the dishwasher?

No. BUNN reservoirs are plastic and can warp or crack in the heat of a dishwasher. Hand-wash with warm water and a soft cloth only. The rubber gasket can also harden if exposed to high heat.

What if vinegar smell stays in the reservoir after cleaning?

Rinse the reservoir five to six times with fresh water instead of three. If the smell persists, fill it with plain water, install it on the machine, and run two full brew cycles with water only. The heat from brewing helps remove lingering vinegar odor.

How often should I descale the whole machine, not just the reservoir?

Run a full descaling cycle through the brew basket once a month if you have hard water, or every two to three months with soft or filtered water. If water flows slowly or the machine takes longer to brew, descale when ready.

Is it safe to use commercial descaling products instead of vinegar?

Yes. BUNN's official descaling solution is formulated for their machines and works well. Follow the package instructions for the correct ratio. Vinegar works too, but some people prefer commercial products because they rinse out faster and leave no smell.

What causes white buildup to come back so quickly?

Hard tap water has high mineral content, so deposits return fast. Switch to filtered water, or empty and rinse the reservoir more often — every three to four days instead of weekly. You can also run a descaling cycle more frequently to prevent thick buildup from forming.