Is water important for coffee? A deep dive into brewing chemistry

January 2, 2026 •

4 min read

According to the Specialty Coffee Association (SCA), water makes up approximately 98-99% of a coffee brew, which means its characteristics are paramount to the final taste. Therefore, is water important for coffee? The answer is an unequivocal yes, and understanding this truth is the first step toward brewing a better cup every time.

Quick Summary

Water quality is a critical, often-overlooked factor in brewing coffee that affects extraction, flavor, and acidity. Mineral content, pH balance, and temperature all play a role in creating the ideal water profile for a balanced and flavorful cup, ensuring consistency and preventing off-tastes.

Key Points

Water makes up over 95% of your coffee: The quality of your water is fundamentally important to the final taste of your brew, just as important as the beans themselves.
Minerals control extraction: The right balance of minerals like calcium and magnesium is needed for optimal flavor extraction. Too many minerals can cause bitterness, while too few can result in a flat taste.
Chlorine ruins flavor: Tap water treated with chlorine can add an unpleasant, chemical taste and odor. Using an activated carbon filter can remove this, leading to a cleaner cup.
Temperature affects extraction rate: Water temperature should be between 195°F and 205°F (90-96°C). Water that is too hot can over-extract and lead to bitterness, while water that is too cool will under-extract and taste sour or weak.
Custom water for better results: Using distilled or reverse osmosis water with added minerals (from a product like Third Wave Water) offers maximum control for precise, consistent brewing results that meet SCA standards.
Hard water damages equipment: High mineral content in hard water leads to limescale buildup in coffee makers, reducing efficiency and lifespan.
Alkalinity affects acidity: Water's alkalinity acts as a buffer. High alkalinity can neutralize pleasant coffee acids, while low alkalinity can cause an overly sour taste.

The Science of Water: Understanding Extraction

Water acts as a solvent, and its chemical makeup directly influences how it interacts with coffee grounds to extract flavor compounds. This is a delicate process, and the wrong type of water can either prevent adequate extraction or pull too many bitter compounds from the grounds, leading to a less than ideal result. Three key chemical factors define your water's impact on coffee: mineral content, pH, and temperature.

Mineral Content: Hard vs. Soft Water

The mineral content, primarily the presence of calcium and magnesium ions, is referred to as water's 'hardness'.

Hard Water: Contains a high concentration of minerals. While a certain level of minerals is necessary to pull flavor from coffee, excessively hard water can lead to over-extraction. The high mineral content can inhibit proper flavor extraction and leave the coffee tasting bitter, dull, or chalky. Hard water is also a leading cause of limescale buildup in brewing equipment, shortening its lifespan.
Soft Water: Has a low mineral concentration. Water that is too soft, or completely demineralized like distilled water, will under-extract the coffee. This can result in a flat, insipid, and overly acidic or sour-tasting brew because there aren't enough minerals to facilitate the chemical reactions needed for a balanced extraction.
The Right Balance: The ideal water has a moderate mineral content, allowing for a balanced and harmonious flavor extraction. Some minerals, like magnesium, can actually enhance sweetness and complexity.

pH Level and Alkalinity

Water's pH measures its acidity or alkalinity. For optimal coffee extraction, water should be close to neutral, with a pH between 6.5 and 7.5. Alkalinity is the water's ability to resist changes in pH and is often referred to as 'carbonate hardness'.

High Alkalinity: If water has high alkalinity, it will neutralize the coffee's natural acids, resulting in a flat, dull, and less complex flavor profile.
Low Alkalinity: Water with low alkalinity lacks a proper buffer, allowing the coffee's acidity to dominate and potentially creating a sharp, sour taste.

Contaminants: The Bad Actors

Beyond basic mineral content, tap water can contain impurities that directly harm coffee flavor. One of the most common is chlorine, which municipal water treatment facilities use as a disinfectant. Even small amounts of residual chlorine can impart an unpleasant, chemical-like taste and odor to your final cup. Activated carbon filters are highly effective at removing chlorine and other organic impurities, ensuring a cleaner taste.

Optimizing Your Water: A Comparison of Options

Achieving the perfect water profile can be accomplished through various methods, from simple filtration to creating a custom blend. Here's a look at common options for home brewers.


Water Source	Pros	Cons	Ideal For
Tap Water	Readily available and inexpensive.	Quality varies greatly by region, often containing chlorine and inconsistent mineral content.	Casual coffee drinkers who are satisfied with the local water taste.
Filtered Tap Water	Removes chlorine and impurities via a simple pitcher or faucet filter.	Doesn't precisely control mineral content or hardness; effectiveness diminishes over time.	Most home brewers looking for a simple, cost-effective upgrade to their coffee quality.
Bottled Water	Often clean and free of chlorine; provides a consistent profile.	Mineral content can be too high or too low depending on the brand. Environmental impact from plastic bottles.	Testing and experimentation to find a specific mineral profile; occasional use.
Distilled + Additives	Offers complete control by starting with a blank slate and adding mineral packets.	Requires an upfront purchase of distilled water and mineral kits; more effort.	Enthusiasts and professionals who want precise, consistent water profiles.
Reverse Osmosis + Remineralization	Gold standard for consistency and control; removes nearly all impurities.	High initial investment for the system; requires remineralization to be suitable for coffee.	Serious coffee professionals and advanced enthusiasts.

Practical Steps for Better Coffee

Taste Test Your Water: Brew two cups of coffee side-by-side: one with your regular tap water and one with a recommended bottled water like Volvic. Notice the differences in flavor clarity, acidity, and body. This exercise highlights the importance of water quality. If your tap water tastes bad on its own, it will ruin your coffee.
Use a Simple Filter: For most people, a basic activated carbon pitcher filter is the easiest way to drastically improve their coffee. It removes off-flavors from chlorine and other contaminants with minimal effort.
Explore Mineral Additives: For enthusiasts wanting more control, products like Third Wave Water offer pre-mixed mineral packets designed to be added to distilled water. These are calibrated to Specialty Coffee Association (SCA) standards and can unlock new flavor dimensions.
Consider Temperature Control: In addition to water quality, temperature is critical. Optimal brewing temperature is generally between 195–205°F (90–96°C). A temperature-controlled kettle can help you precisely dial in your brewing for better extraction, as water that is too hot or too cold can lead to an unbalanced brew.
Measure Your Water: Using an inexpensive TDS (Total Dissolved Solids) meter can help you monitor the mineral content of your water and ensure consistency. The SCA recommends a TDS range of 75–250 ppm for brewing specialty coffee.

Conclusion

It is clear that water is not just a passive ingredient but an active and vital component in coffee brewing. Its quality, mineral content, and temperature are as important as the beans and brewing method themselves. From a simple filter to advanced mineral manipulation, improving your water can be the most significant and rewarding step you take on your coffee journey. By paying attention to this often-overlooked factor, you can elevate every cup from good to truly exceptional.

Third Wave Water – The Search for Perfect Coffee Water

Frequently Asked Questions

If your coffee still tastes off despite high-quality beans, the water is a very likely culprit. Impurities, incorrect mineral balance, or chlorine in your water can significantly degrade flavor, muting the coffee's natural notes or causing bitterness.

You can use tap water, but its quality varies greatly by location. Many tap water sources are too hard, contain chlorine, or have an imbalanced pH, all of which can negatively impact the taste of your coffee. At a minimum, filtering your tap water is highly recommended.

No, distilled water is not good for coffee on its own. It lacks the essential minerals (like calcium and magnesium) that are necessary to properly extract flavor compounds from the coffee grounds, resulting in a flat, lifeless, and weak-tasting brew.

The ideal water temperature for brewing coffee is generally between 195°F and 205°F (90°C and 96°C). Using a temperature-controlled kettle allows for precision, as too-hot water can lead to bitterness and too-cold water can result in under-extraction.

Minerals like calcium and magnesium play a crucial role in binding to flavor compounds during extraction. Too many minerals can over-extract the coffee, leading to bitterness, while too few can cause under-extraction and a flat taste. The right balance brings out the coffee's unique and complex flavors.

Water hardness refers to the concentration of dissolved minerals, primarily calcium and magnesium. It's important because it directly impacts the extraction process. Hard water can cause over-extraction and bitterness, while very soft water can cause under-extraction and sourness.

The simplest method is to taste the water. If it tastes odd or metallic, it will likely affect your coffee. For a more scientific approach, you can use an inexpensive Total Dissolved Solids (TDS) meter to measure mineral content or buy test strips for more detailed analysis.