Cleaning the Bunn Coffee Maker Water Reservoir

Quick answer

• Use a descaling solution or a vinegar/water mix to break down mineral buildup.
• Always unplug the machine before cleaning.
• Rinse thoroughly to remove any cleaning solution residue.
• Run a few cycles with fresh water afterward.
• Regular cleaning prevents clogs and improves brew quality.
• Don’t forget to clean the brew basket and carafe too.

What this problem usually is (and is not)

This guide is about cleaning the internal water reservoir of your Bunn coffee maker. That’s where the water sits before it heats up and brews.

• This is not about cleaning the exterior of your machine.
• This is not about fixing electrical issues or leaks.
• It’s about tackling mineral deposits, gunk, and potential mold.
• We’re focused on improving taste and machine longevity.
• Don’t expect miracles if your machine has deeper mechanical problems.
• Safety first: always unplug before you start poking around.

Likely causes (triage list)

Mineral Buildup (Scale)

This is the big one. Hard water leaves behind calcium and magnesium deposits. You might see white, chalky stuff inside. It can clog water lines and affect heating. Confirm by looking for crusty buildup.

Coffee Oils and Residue

Over time, coffee oils can accumulate, especially if you don’t clean regularly. This can make your coffee taste stale or bitter. Look for brown, sticky residue.

Stagnant Water Issues

If the machine sits unused for a while, the water in the reservoir can become stagnant. This can lead to mold or unpleasant odors. A quick visual inspection might reveal cloudiness or slime.

Filter Issues (Less Likely for Reservoir)

While not directly a reservoir problem, a clogged water filter upstream can sometimes lead to poor water flow into the reservoir, indirectly affecting how it behaves. This is rare for internal reservoir cleaning.

Machine Setup

How you fill the reservoir matters. If you’re using tap water directly from a hard water source without a filter, scale will build up faster.

Fix it step-by-step (brew workflow)

This is how you tackle that reservoir gunk. It’s not rocket science, just a bit of elbow grease and patience.

1. Unplug the Machine: Always the first step. Seriously, don’t skip this. Safety first, always.

• Good looks like: The power cord is out of the wall.
• Common mistake: Forgetting to unplug and getting a shock. Don’t be that guy.

2. Empty the Reservoir: Pour out any remaining water. If it looks gross, well, that’s why you’re here.

• Good looks like: The reservoir is completely empty.
• Common mistake: Leaving old water in and diluting your cleaning solution.

3. Prepare Cleaning Solution: You have options.

• Option A (Descaler): Follow the instructions on your Bunn-approved descaling solution. They’re made for this.
• Option B (Vinegar Mix): Mix equal parts white vinegar and water. For a standard Bunn, this might be around 3-4 cups of each.
• Good looks like: You have a clear solution ready to go.
• Common mistake: Using harsh chemicals not meant for coffee makers, like bleach. That’s a bad idea.

4. Pour Solution into Reservoir: Carefully pour your chosen cleaning solution into the water reservoir. Fill it to the usual max line if possible.

• Good looks like: The solution is fully in the reservoir, not spilling.
• Common mistake: Overfilling and having it spill out the sides.

5. Let it Sit (Soak Time): Let the solution sit in the reservoir for at least 30 minutes, or up to an hour for heavy buildup. This gives it time to break down the gunk.

• Good looks like: The solution is just chilling in there, doing its work.
• Common mistake: Rushing the process. Patience is a virtue, especially with coffee makers.

6. Run a Brew Cycle (with Solution): Place your carafe under the brew basket. If your machine has a “brew” or “off” switch that lets water run through without heating, use that. Otherwise, run a full brew cycle. Make sure you’re not brewing coffee at this stage!

• Good looks like: The cleaning solution is flowing through the machine into the carafe.
• Common mistake: Forgetting to put the carafe in place and making a mess.

7. Discard the Solution: Pour the brewed cleaning solution from the carafe down the drain.

• Good looks like: The carafe is empty, and the solution is gone.
• Common mistake: Thinking it’s clean enough to drink or reuse. Nope.

8. Rinse the Reservoir: Fill the reservoir with fresh, clean water.

• Good looks like: Clean water going in.
• Common mistake: Using the same dirty water.

9. Run Rinse Cycles: Run at least 2-3 full brew cycles using only fresh water. This is crucial for removing any lingering cleaning solution or vinegar smell/taste.

• Good looks like: Clear water brewing through. No funny smells.
• Common mistake: Only running one rinse cycle. You’ll taste it later.

10. Clean Brew Basket & Carafe: While the machine is rinsing, give your brew basket and carafe a good scrub with soap and water.

• Good looks like: Sparkling clean brew accessories.
• Common mistake: Neglecting these parts and reintroducing old coffee oils.

11. Wipe Down Exterior: Give the outside of your Bunn a quick wipe with a damp cloth.

• Good looks like: A clean exterior.
• Common mistake: Leaving dust and coffee splashes on the machine.

Prevent it next time

An ounce of prevention is worth a pound of cure, right? Keep your Bunn happy.

• Descale Regularly: Aim for every 2-3 months, or more often if you have hard water. Check your manual for Bunn’s recommendation.
• Use Filtered Water: This is the biggest game-changer for preventing scale. A good pitcher filter or a plumbed-in filter makes a huge difference.
• Clean the Carafe Daily: A quick rinse after each use prevents oil buildup.
• Scrub the Brew Basket Weekly: Don’t let coffee grounds fester.
• Empty Reservoir if Unused: If you won’t use it for a few days, empty the reservoir.
• Wipe Down Exterior Often: Keep it looking sharp.
• Check Water Lines (Visually): Occasionally, look for obvious clogs or leaks around the water path.
• Use Correct Coffee-to-Water Ratio: Too much coffee can clog filters, affecting water flow.
• Store Coffee Properly: Keep beans in an airtight container away from light and heat.
• Regular Machine Cleaning: Don’t wait for problems to appear.

Common mistakes (and what happens if you ignore them)

Mistake	What it causes	Fix
Not unplugging the machine	Electric shock, damage to the machine	<strong>Always unplug before cleaning.</strong>
Using harsh chemicals (bleach, ammonia)	Damage to internal components, toxic residue, unsafe coffee	Use only Bunn-approved descalers or white vinegar/water mix.
Not rinsing thoroughly	Bitter, vinegary, or chemical-tasting coffee	Run at least 2-3 full cycles with fresh water after cleaning.
Using tap water in a hard water area	Rapid scale buildup, clogged water lines, reduced heating efficiency	Use filtered water or a water softener. Descale more frequently.
Forgetting to clean the brew basket/carafe	Old coffee oils make fresh coffee taste stale or bitter	Clean these parts daily or weekly as needed.
Ignoring signs of scale buildup	Slow brewing, weak coffee, machine failure, potential water damage	Descale immediately when you notice issues.
Not letting descaler soak	Ineffective cleaning, scale remains	Allow adequate soaking time (30-60 minutes) for the descaler to work.
Using hot water for cleaning solution	Can warp plastic parts or be less effective for dissolving certain mineral types	Use room temperature water for vinegar mixes. Follow descaler instructions.
Not emptying reservoir before cleaning	Dilutes cleaning solution, less effective	Ensure reservoir is empty before adding cleaning solution.
Forcing parts or components	Broken parts, leaks, irreparable damage	Be gentle. If something feels stuck, re-evaluate or check the manual.

Decision rules (simple if/then)

• If your coffee tastes off, then descale your machine because mineral buildup or old coffee oils are likely culprits.
• If your machine is brewing slower than usual, then descale it because scale can clog the water lines.
• If you see white, chalky deposits inside the reservoir or on heating elements, then descale immediately because this is mineral scale.
• If you haven’t descaled in over six months, then descale your machine as a preventative measure.
• If you have very hard water, then you should descale more frequently (e.g., every 1-2 months).
• If your machine smells musty, then clean the reservoir and run rinse cycles because stagnant water can grow mold.
• If you’re unsure about a specific cleaning product, then check your Bunn manual or contact their support because using the wrong cleaner can damage the machine.
• If you notice a persistent chemical taste after cleaning, then run more fresh water rinse cycles because you likely didn’t remove all the descaler.
• If you’re using a Bunn coffee maker regularly, then aim to descale every 2-3 months as a baseline.
• If you want to extend the life of your machine and improve coffee taste, then commit to regular cleaning and descaling.
• If you’re experiencing significant leaks or electrical issues, then stop using the machine and contact a qualified technician because these are safety concerns beyond simple cleaning.

FAQ

How often should I clean my Bunn coffee maker reservoir?

For most users, descaling every 2-3 months is a good starting point. If you have very hard water or use your machine heavily, you might need to do it more often.

Can I use bleach to clean my Bunn reservoir?

Absolutely not. Bleach is too harsh and can damage your machine’s internal components, leaving behind toxic residue that will make your coffee unsafe to drink. Stick to descaling solutions or vinegar.

What’s the best way to get rid of mineral buildup?

A good quality descaling solution specifically made for coffee makers is usually best. A 1:1 mix of white vinegar and water is a common DIY alternative, but it requires more thorough rinsing.

My coffee tastes funny after cleaning. What did I do wrong?

You probably didn’t rinse enough. After descaling, run at least 2-3 full cycles with fresh water to ensure all cleaning solution residue is gone.

Does filtered water really make a difference for my reservoir?

Yes, a big one! Filtered water significantly reduces the mineral content, which means much less scale buildup in your reservoir and internal components. It’s one of the easiest ways to keep your machine running smoothly.

Can I leave cleaning solution in the reservoir overnight?

While some descalers might suggest longer soak times, it’s generally best to stick to the recommended 30-60 minutes. Leaving solutions in for too long could potentially damage some materials.

My Bunn reservoir has a weird smell. What should I do?

This usually indicates stagnant water or potential mold growth. Clean the reservoir thoroughly with a descaling solution or vinegar mix, and then run multiple fresh water rinse cycles.

What this page does NOT cover (and where to go next)

• Troubleshooting electrical faults: If your machine won’t power on, or has sparks, don’t try to fix it yourself.
• Repairing broken components: This guide is for cleaning, not for fixing cracked plastic or faulty heating elements.
• Specific Bunn model instructions: While general principles apply, always check your specific Bunn model’s manual for detailed care.
• Plumbing and water line installation: If you’re dealing with a plumbed-in Bunn, that’s a different ballgame.
• Advanced coffee brewing techniques: This is about machine maintenance, not pour-over perfection.