Empty and rinse the reservoir first

Start by unplugging the Bunn machine and letting it cool for at least 30 minutes. Remove the water reservoir from the top of the machine — on most Bunn models, it lifts straight out. Empty any remaining water into a sink.

Rinse the inside of the reservoir thoroughly with hot tap water. Use your hand or a soft cloth to wipe down the interior walls and bottom. Pay attention to corners and seams where mineral deposits and algae can hide. If you see visible buildup, fill the reservoir halfway with hot water and let it sit for 10 minutes before scrubbing again with a soft brush or cloth.

Do not use abrasive scrubbers or bleach on the reservoir itself, as these can damage the plastic and leave residue that affects your coffee taste.

Key Takeaways

  • Unplug the machine and remove the reservoir, then rinse it with hot water and wipe the interior walls and bottom by hand.
  • Run a cleaning cycle with a commercial coffee maker descaler or white vinegar mixed with water through the brew basket to clear mineral buildup inside the machine.
  • After descaling, run two full reservoirs of plain water through the machine to rinse out all cleaning solution before brewing coffee again.
  • Clean the spray head and brew basket weekly with hot water and a soft brush to prevent mold and coffee oil buildup.
  • Replace the reservoir every 12 to 18 months if you notice discoloration, cracks, or a plastic smell that does not go away after rinsing.

Run a descaling cycle through the brew basket

Fill the clean reservoir with a descaling solution. Bunn sells its own descaler, but white vinegar works just as well — use a 1:1 ratio of white vinegar to water. For a full reservoir, that is roughly 30 ounces of vinegar and 30 ounces of water.

Place a large empty pitcher or bowl under the brew basket to catch the liquid. Insert the reservoir back into the machine, plug it in, and let the heating element warm up for about 15 minutes. Then pour the vinegar solution into the brew basket as if you were making coffee, but do not add grounds. Let the solution drip through into your pitcher.

Once the reservoir is empty, let the machine sit for 15 to 20 minutes. This gives the descaler time to break down mineral deposits inside the heating element and internal lines. Then repeat the process — refill the reservoir with the remaining descaling solution and run it through again.

Flush the system with plain water

After descaling, you must rinse the machine thoroughly. Fill the reservoir with fresh tap water and run it through the brew basket into your pitcher, just as you did with the vinegar. Discard the water in the pitcher.

Repeat this rinse cycle at least two more times with fresh water each time. This removes all traces of vinegar or descaler from the heating element and internal lines. If you skip this step or do it only once, your next pot of coffee will taste sour or chemical.

On the final rinse, you can brew directly into your coffee cup to check the taste. If you still detect vinegar, run one more cycle of plain water through.

Clean the spray head and brew basket weekly

The spray head — the part that distributes water over the grounds — collects coffee oils and mineral deposits that slow water flow and affect flavor. Remove it by lifting the brew basket out of the machine. The spray head usually lifts or twists out from underneath.

Soak the spray head in hot water for 5 minutes, then use a soft brush or old toothbrush to scrub away any buildup. Pay special attention to the small holes where water comes out. Rinse thoroughly and replace it.

Wash the brew basket itself with hot soapy water and a soft cloth. Dry it completely before putting it back in the machine. Leaving it wet can promote mold growth inside the basket.

Know when to replace the reservoir

Even with regular cleaning, Bunn reservoirs wear out. If you notice cracks, permanent discoloration that does not rinse away, or a plastic smell that lingers after multiple rinses, the reservoir has degraded and should be replaced. Bunn sells replacement reservoirs for most models, and they typically cost between $15 and $30.

A cloudy or yellowed reservoir does not affect function, but a cracked one can leak and damage the machine. If the plastic smells like chemicals or rubber even after thorough rinsing, the material is breaking down and may leach into your water.

Most Bunn reservoirs last 12 to 18 months with regular use and weekly cleaning. If you use your machine daily, plan to replace it sooner.

Descale every 30 to 60 days depending on water hardness

How often you descale depends on your water. If you have hard water — water with high mineral content — descale every 30 days. If your water is soft, you can descale every 60 days. You can tell your water is hard if you see white or tan buildup on the inside of the reservoir or if coffee brews more slowly than usual.

Some Bunn machines have a cleaning light that turns on when descaling is due. Check your manual to see if yours has this feature. If it does, follow the light's schedule rather than guessing.

Descaling takes about 30 minutes total and prevents mineral buildup that can damage the heating element and shorten the machine's life. It also keeps your coffee tasting fresh instead of bitter or flat.

Frequently Asked Questions

Can I use vinegar instead of Bunn descaler?

Yes. White vinegar works as well as commercial descaler for breaking down mineral deposits. Use a 1:1 ratio of vinegar to water. The main difference is that Bunn descaler may have a milder smell, but both clean the machine equally well. Rinse thoroughly afterward either way.

What if water is leaking from the bottom of the machine?

Check that the reservoir is seated properly — it should click or lock into place. If it is seated correctly and water still leaks, the reservoir may have a crack. Remove it and inspect the bottom and sides under bright light. A cracked reservoir must be replaced. Do not use the machine until you do, as water can damage internal components.

How do I know if my machine needs descaling?

Coffee brews noticeably slower than it used to, or you see white or tan buildup inside the reservoir. Some machines also have a cleaning indicator light. If you have hard water, descale every month even if you do not see visible buildup yet.

Can I soak the entire brew basket in vinegar?

Yes, soaking the brew basket in a 1:1 vinegar-and-water solution for 15 to 20 minutes helps remove stubborn coffee oil buildup. Scrub gently with a soft brush afterward and rinse thoroughly with hot water before using the machine again.

Is it safe to drink the first pot after descaling?

No. Always run at least two full reservoirs of plain water through the machine after descaling before brewing coffee. This removes all vinegar or descaler residue. Taste the water from the second rinse — if it still smells like vinegar, run a third cycle.