How To Clean And Descale A Coffee Machine Reservoir. (Properly)

How to clean a coffee machine reservoir

As with any appliance, coffee machines need to be cleaned regularly to maintain good working order and cleanliness. Although it seems unlikely, one of the dirtiest places in a coffee machine is the reservoir that holds the water.

Over time, bacteria, mineral deposits, and mold can build up in the reservoir, degrading the quality of your coffee and potentially damaging your coffee machine.

Coffee reservoirs are usually detachable and can be easily cleaned with hot soapy water. If the reservoir contains mold or mineral buildup, a vinegar and water solution should be used to descale the reservoir.

In this article, we’ll look at why it’s important to clean your coffee reservoir even when it looks clean, how to tell when your reservoir may need descaled and compare some popular cleaning and descaling methods including vinegar, hydrogen peroxide, soapy water, and coffee cleaning tablets.

Why It’s Important to Clean the Reservoir

Of all the locations in your coffee maker, the reservoir probably seems like the least important part to clean. Depending on what type of coffee machine you have, the reservoir likely only holds water, so it’s not obvious how it could become dirty.

Unfortunately, since the reservoir seems to clean, it’s often overlooked when it comes to cleaning which can lead to some nasty germs and mold developing.

Let’s look at just some of the reasons you should clean your reservoir regularly:

1. To Eliminate Germs and Bacteria

Although often overlooked, coffee machine reservoirs are the perfect breeding ground for germs and bacteria if not cleaned and dried out regularly.

Bacteria like E-Coli and Salmonella thrive in damp, dark environments.

According to researcher Mindy Costello from the National Sanitation Foundation, coffee machine reservoirs are the fifth most germ-ridden place in the average home, being only slightly less germy than a pet bowl.

In an office setting, it’s even more striking. Microbiologist Charles Gerba from the University of Arizona discovered that coffee break rooms and kitchens are the dirtiest places in an average office.

2. To Eliminate Mold

In 2011, the National Sanitation Foundation (NSF) published the International Household Germ Study

Several appliances and household locations were tested, and it was discovered that in 50% of cases, coffee reservoirs contained mold or yeast

Mold presents a serious health risk, so it’s crucially important to clean it away.

3. To Descale / Decalcify

If you live in an area where the water is rich in minerals like calcium and magnesium (often called soft water), you’ll already be familiar with the neverending battle against limescale and mineral buildup.

You may notice a white, chalky residue building up over time anywhere that’s frequently in contact with your tap water.

It’s important to descale your coffee reservoir periodically as this mineral buildup can impact the ability of your coffee machine to function normally.

4. To Remove Coffee Residue

Depending on the specific type of coffee maker you have, it may be possible that some coffee residue ends up in the water reservoir.

This is important to clean because any leftover coffee residue will become burnt and stale, provide a breeding ground for mold and bacteria, and ruin the taste of your future brews.

How To Clean Your Coffee Machine Reservoir (Three Methods)

Do you have a Keurig Coffee Machine?
Check out my guide to cleaning your Keurig coffee machine with vinegar where I provide step-by-step instructions specifically designed for Keurigs.

If you just need to clean your reservoir out, these methods are perfect for you. If you have a problem with limescale, you may want to try the descaling methods mentioned in the descaling methods section of this article instead.

1. Use Hot Soapy Water

Remove your reservoir and wash it with hot soapy water using a non-abrasive sponge or cloth. Hot soapy water will remove any bacteria, coffee residue, or mold present in your reservoir.

Once you’ve cleaned out the reservoir, make sure to thoroughly rinse it of any suds and let it dry before putting it back into your machine.

2. Use a Dishwasher

Most coffee machine reservoirs are dishwasher-safe and you can wash them alongside your other utensils and kitchenware.

If you’re not sure, check the instructions from the manufacturer. Most reservoirs made from glass or aluminum will be perfectly safe for the dishwasher.

3. Use a Coffee Machine Cleaning Tablet

An alternative method for manually cleaning or using the dishwasher is to use a coffee machine cleaning tablet.

Cleaning tablets work similarly to dishwasher tablets and will also remove limescale from your coffee machine.

To use the tablets, simply add one tablet to your filled reservoir and run it through the machine. Tablets are also available in a stronger liquid format for dealing with limescale.

How Often Should You Clean Your Coffee Reservoir?

Your coffee reservoir should be cleaned out and dried after every use to prevent bacteria or mold from developing in the stagnant water.

How To Descale Your Coffee Maker Reservoir (3 Methods)

Descaling your coffee machine is critical to ensure your coffee machine keeps working correctly. 

To descale your coffee machine, regular hot water might not be enough. For heavier mineral deposits, the best option is to use a weak acid like vinegar or dilute hydrogen peroxide to remove the limescale, followed by a thorough rinse.

1. Use Vinegar to Descale Your Reservoir

Vinegar is slightly acidic, which means that it’s great for dissolving calcium and magnesium deposits that build up over time in areas with mineral-right water sources.

To descale your coffee machine reservoir, use a solution of 50% distilled white vinegar and 50% cold water.

Let the vinegar solution sit in the reservoir until the limescale is dissolved, then rinse out and let the reservoir dry before adding it back into your coffee machine.

2. Use a Hydrogen Peroxide Solution

Hydrogen peroxide sounds scary, but it’s a very common household chemical. It’s found in many household cleaners and cosmetic products and works great against limescale.

The best option is to use a very dilute solution. You can buy pre-mixed bottles of 3% food-safe hydrogen peroxide solution on Amazon, and it works just the same way as vinegar.

Make sure you thoroughly rinse the reservoir after you’ve cleaned it.

3. Use a Coffee Machine Cleaning Tablet or Solution

There are a few specialist solutions available to buy that have been created to make the descaling process as simple as possible.

These options clean and descale your coffee machine without you having to use any soap, vinegar, or hydrogen peroxide.

Coffee Machine Cleaning Tablets are available on Amazon. They are easy to use (just add them to the reservoir and fill them with water) and cheap to buy.

There are also pre-mixed solutions available, which work in the same way as the vinegar or hydrogen peroxide methods mentioned above.

Check the current price on Amazon: Coffee Machine Descaling Solution

How Often Should You Descale Your Coffee Maker Reservoir?

You need to descale your coffee machine reservoir periodically, the exact timescale will depend on how ‘hard’ or ‘soft’ the water is where you live. As a very rough guide, your machine should be descaled at least once every three months.

Signs You May Need to Descale

Here are some things you can look out for that may indicate it’s time to give your machine a deep descaling treatment.

  • Brewing takes longer than usual
  • Cleaning light indicator is illuminated
  • Reduced or stopped water flow
  • Leaking or dripping
  • Your machine doesn’t heat up correctly
  • Unusual gurgling or sputtering noises

Read More: How To Fix a sputtering moka pot

How To Prevent Calcium / Mineral Buildup in your Reservoir

Calcium and other minerals are present in most water sources across the world. If you live in an area with high mineral content in your water, you can reduce the impact of calcium buildup by installing a water filter or using filtered water in your coffee machine.

Even if you use filtered water, you will likely still need to descale your coffee machine a few times every year.

Does Cleaning the Coffee Reservoir Affect the Taste?

Cleaning out your coffee machine reservoir won’t affect the taste of your coffee, but if you don’t clean it, any stale coffee residue, mold, bacteria, or limescale that builds up will all reduce the quality of your brew

Cleaning and descaling will remove them to get your brew quality back to normal.

Best Practices to Keep Your Reservoir Clean

Aside from cleaning your reservoir regularly, the best way to make sure it doesn’t become dirty is to always empty it out and leave the lid open between uses.

This will ensure any moisture is removed, leaving no place for bacteria to multiply.


To sum up, coffee machine reservoirs are actually quite dirty, even though they only hold water.

Bacteria, mold, coffee residue, and limescale can all build up in the reservoir if it’s not kept clean and descaled regularly.

The simplest way to clean your reservoir is simply to use hot soapy water, but if there is limescale buildup it may be necessary to use vinegar or a coffee machine cleaning tablet to remove the limescale before you can wash it.

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