Is Reverse Osmosis Water Bad for Coffee Makers?

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So you got yourself a brand new gadget to make yourself a cup of coffee.

Whether that be a larger-scale coffee machine or a smaller coffee pod extractor, you want to make sure you are only using the best water, to enhance the taste of your drink while also prolonging the life of your equipment.

So, is RO water your best choice? Let’s see.

Key Takeaways

  • Reverse osmosis water that has not been remineralized could be bad for your coffee maker cause such RO water is prone to causing corrosion far more readily than non-RO water.
  • Plain RO water also lacks the minerals needed to extract the flavor out of coffee beans.

Is Reverse Osmosis Water Bad for Coffee Makers?

First of all, is reverse osmosis bad for coffee makers? Yes and no.

Reverse osmosis water is highly pure, and pure water is a highly potent solvent with an exceptional ability to dissolve substances. In fact, distilled and reverse osmosis water with nearly zero dissolved solids is such a powerful solvent that it can extract metals from pipes and boilers in coffee and espresso machines. This extraction can result in corrosion and eventual breakdown of these components.

Therefore, yes, reverse osmosis water can be bad for coffee makers.

At the same time, reverse osmosis water is free from calcium and other minerals, which means it won’t cause clogging when used in a coffee maker – which is good!

coffee maker on kitchen countertop

Does RO Water Affect the Taste of Coffee?

This is another factor to consider: RO water affects the taste of coffee due to its lack of TDS and minerals such as calcium, magnesium, and sodium. These minerals are valuable components of coffee brewing and can affect flavor, aroma, body, and overall taste. For this reason, using water with some TDS content is generally recommended when brewing coffee.

Ideal Water Parameters for Coffee Brewing

Below are the ideal water parameters for coffee brewing as recommended by the SCA.

  • Odor: Clean/Fresh, Odor free
  • Total Chlorine: 0 mg/L
  • Calcium Hardness: 50-175 ppm
  • Total Alkalinity: 40 ppm
  • pH: 7.0 (Acceptable Range: 6-8)

RO water meets the criteria of being free from odor and chlorine. But it usually falls below the range of 50 to 175 ppm calcium hardness. The same goes for total alkalinity. As for water pH, RO water is usually slightly acidic, so this could be fine.

All Pros and Cons of Using RO Water for Coffee Brewing

Benefits of RO Water for Coffee Brewing

  • Chlorine Removal: RO water is free from chlorine, preventing off-flavors in coffee. It’s also free from most other impurities that can affect taste and smell.
  • Harmful Contaminant Removal: RO systems filter out heavy metals, organic compounds, and bacteria, ensuring a cleaner, fresher, and safer cup of coffee.
  • Consistent Taste: With minimal TDS, RO water offers a consistent coffee experience even if municipal water supply taste and smell change.
  • No Clogging: RO water won’t clog your coffee maker with mineral deposits.

Cons of Using RO Water for Coffee Brewing

  • Loss of Beneficial Minerals: The filtration process removes essential minerals like calcium, magnesium, and sodium, potentially resulting in flat or flavorless coffee.
  • Increased Costs: RO systems can be pricey, making them an impractical investment for some, and they contribute to higher water bills and maintenance costs.
  • Time-consuming: Brewing coffee with RO water takes longer, particularly if waiting for filtered water or dealing with an empty storage tank.
  • Corrosive: RO water is a potent solvent. It may cause your coffee maker to corrode.

The Solution: Remineralization

It might be possible to optimize your RO water for making coffee by using a remineralization filter. These filters increase pH and alkalinity while introducing calcium and overall TDS back into the water. To achieve this, you’ll need to ensure the correct minerals are added in appropriate quantities, as shown in this article’s ideal water parameters section.

Once you know what minerals are needed, you can purchase a remineralization filter that adds those specific minerals back into the water. This process should result in better-tasting coffee.

What’s the Best Water for Your Coffee Machine?

The best water for your coffee machine is one that fits within the ideal parameters. This could be in the form of the following.

Tap Water

Your tap water may even be the best for brewing coffee, depending on its chemistry. It is best to have your tap water tested to see if it fits the parameters listed above.

Bottled Water

Bottled water may be feasible, provided its chemistry is optimal for coffee extraction. Many bottled water companies list their mineral composition on their labels, so check before selecting which one to use to brew your morning cup.

Distilled Water

Distilled water is expensive and not at all optimal for brewing coffee, for the same reasons non-remineralized RO water is not optimal….it lacks the required minerals.

If you have any thoughts about the question, is reverse osmosis water bad for my coffee machine, please don’t hesitate to leave a comment below!

About the Author Gene Fitzgerald

Gene Fitzgerald is one of the founders of BOS and currently head of content creation. She has 8+ years of experience as a water treatment specialist under her belt making her our senior scientist. Outside of BOS, Gene loves reading books on philosophy & social issues, making music, and hiking.
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