Coffee water quality shapes how your cup tastes, because water makes up about 94 to 98 percent of brewed coffee. The minerals in that water affect how flavor compounds extract. As a result, the same coffee can taste noticeably different from one water source to another.
Minerals in water change coffee more than most people expect. You can buy great coffee, grind it well and nail your brew time. Yet you can still end up with a flat or chalky cup. Often, the culprit is hiding in plain sight: your tap. Understanding coffee water quality helps you get more out of the coffee you already have.
Why Coffee Water Quality Matters So Much
Water is the solvent that pulls flavor out of coffee grounds. According to SCA News, from the Specialty Coffee Association, water can make up 94 to 98 percent of the drink. So whatever is in your water ends up in your cup, too.
Minerals play an active role. A 2014 study in the Journal of Agricultural and Food Chemistry looked at this with computer modeling. It examined how dissolved sodium, magnesium and calcium interact with coffee compounds. The researchers concluded that controlling these ions changes both the rate and the makeup of extraction. You can read the study summary from the University of Bath.
Water also varies a lot by location. The U.S. Geological Survey defines water hardness as the amount of dissolved calcium and magnesium. It also notes that hard water is especially common in the east-central and western United States. That helps explain why the same coffee can taste different in different cities.
What the Coffee Water Quality Standard Recommends
The Specialty Coffee Association publishes a water standard for brewing coffee. SCA News lists these targets:
- Odor and color. Odor-free and clear.
- Chlorine. 0 mg/L.
- Total dissolved solids (TDS). A target of 150 mg/L, within a range of 75 to 250 mg/L.
- Calcium hardness. A target of 51 to 68 mg/L, within a range of 17 to 85 mg/L.
- Total alkalinity. At or near 40 mg/L.
- pH. A target of 7, within a range of 6.5 to 7.5.
- Sodium. A target of 10 mg/L, and less than 30 mg/L.
You don't need to hit every number at home. However, the standard shows the big picture of good coffee water quality: some minerals, not too many, and no chlorine.
Signs Your Tap Needs Attention
Your water might be the issue if your coffee keeps tasting off despite fresh coffee and good technique. Watch for these signs:
- Chlorine smell or taste. Treatment chemicals in tap water can cover up coffee's aroma.
- Scale in your kettle or brewer. White mineral deposits point to hard water, which the USGS notes can build up in equipment.
- Flat, lifeless flavor. Water with very few minerals, such as distilled water, falls below the SCA's minimum TDS range.
- Chalky or dull taste. Very hard, high-alkalinity water can mute coffee's brightness.
- Changes when you travel. If the same coffee tastes different away from home, water is a likely reason.
Testing your tap water is easy. An inexpensive TDS meter gives you a baseline number to compare with the SCA's range. Many water utilities also publish an annual water quality report with hardness details. Your coffee water quality check can start right there.
Simple Ways to Improve Your Coffee Water Quality
You don't need expensive equipment to make a difference. A basic activated carbon pitcher filter is commonly used to reduce chlorine taste and odor. Some cities use chloramine instead of chlorine. In that case, check that your filter is certified to reduce it, since not every filter does.
If your water is very hard, try mixing filtered tap water with distilled water. That brings the mineral content down. Just avoid going all the way to distilled, which would leave too few minerals. Some coffee enthusiasts go further and add mineral packets to purified water to hit a specific recipe.
Bottled spring water can also work, though mineral content varies by brand. Check the label for a mineral or TDS figure if the bottle lists one. For most home brewers, filtered tap water is a practical, affordable starting point.
Temperature matters as much as what's in the water. Our guide to coffee water temperature covers the ideal range for each brewing method.
Better Water, Better Morning Ritual
Paying attention to coffee water quality can change your daily cup without changing your coffee or your brewer. The same grounds that tasted flat yesterday may taste brighter with better water. It's one of the simplest upgrades you can make. For the other big variable, see our guide to coffee grind size.
Adaptogen is a functional coffee blended with seven functional mushrooms: reishi, maitake, chaga, shiitake, cordyceps, turkey tail and lion's mane. Like any coffee, it tastes its best when you brew it with clean, well-balanced water.
Written by Carlos Leon, Founder of Earth Co
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Frequently Asked Questions
Does coffee water quality really affect taste that much?
Yes. According to SCA News, water can make up 94 to 98 percent of brewed coffee. The minerals in it affect how flavor compounds extract. As a result, a new water source can change how the same coffee tastes.
Is distilled water a good choice?
It's not ideal on its own. Distilled water has almost no dissolved minerals. That puts it below the SCA's recommended range of 75 to 250 mg/L TDS. Filtered tap water or spring water with moderate minerals usually works better.
How do I know if my tap water is too hard?
Scale in your kettle or coffee maker is a common sign of hard water. You can also check your utility's annual water quality report or test your water at home. The USGS classifies water above 120 mg/L as hard.