Like Water For Coffee

by laura everage on June 25, 2013 · 1 comment


Did you know coffee is nearly 99% water? Which means the quality of water is important  to the quality of the final cup of coffee. To learn more about what you can do to ensure you’re using quality water to brew your coffee, we turn to Samantha Joyce of Seattle Coffee Gear for some insight.

From the ancient mariners to the modern world to tales of space exploration in the future, our civilization revolves around water. The hunt for it, the control of it and the quality of it is important. Water is what makes life, and thus coffee, possible. We are 53% water. Coffee is 98.5% water. To me, this indicates we need to drink more coffee.

There is more science than magic involved in brewing a perfect cup of coffee. Molecules and minerals, ions and anions are all doing their thing inside your favorite coffee-making device. While it is admirable to want to know those particulars, it is more fun to study single-origin microlots in Colombia rather than the principle of ion exchange. You know what makes specialty coffee so special. Now fill your favorite mug and sit back while we describe (in broad coffee-colored strokes) what makes good water.

Here is the basic rule of thumb: Use water that you enjoy drinking to make coffee. Pour a glass of water for yourself. How does it smell, look and taste?  Do not overthink it. If it the drinking water appeals to you then that’s what matters most. If you find it lacking in one of these subjective categories then we will break down the objective science to rectify your lackluster water situation.

Water Odor

Bleach, chemical or medicinal smell may be attributed to a local water authority’s addition of chlorine to the water

Rotten egg or sewage odor may be caused by bacteria growing in your water heater or plumbing

Musty, moldy or earthy odor is more common in well systems where bacteria is introduced from surface run off or inside the pressure system

Odor problems are generally solved by filtering your water. For larger issues a whole house water filtration system may be necessary.

Water Color

Cloudy water is sometimes caused by a temperature variation especially in winter. Cold water holds more air than warm water. This could also be caused by pressure in your plumbing.

Rust colored water or sink residue is usually from rusty plumbing pipes. Pink colored water or sink residue is from the addition of fluoride reacting to minerals in the water.

Any other color: Have your water and plumbing system checked out.

While a glass of cloudy water will clear on its own within a few minutes, rust or pink colored water should be filtered. Any other color should warrant a call to your local water authority for further tests.

Water Taste

There is a subjective determination to find any unpleasant mineral taste from chlorine, fluoride, iron or sulphur in the source water or plumbing system. If a glass of water does not taste good filter it. If filtering is not enough or you are curious what quantifies the best possible water for brewing, the Specialty Coffee Association of America (SCAA) has published the following guidelines:

Total dissolved solids – While this sounds kind of gross, there are minerals and things in your water that add to the flavor. These are acceptable within a range of 150ppm (0.15%).

Calcium hardness – Hard water is not good for you or your coffee making equipment. This is the cause of scale buildup. The range is 17mg/L to 85mg/L with a target of 68mg/L [Note here, you still need some].

Alkalinity – This factor is influenced by the source water and runoff over rocks and soils, salts and certain plants. The target is at or near 40mg/L. pH – A neutral 7.0 is preferred with a range of 6.5 – 7.5 acceptable.

Sodium level – At or near 10mg/L.

Many municipalities publish an annual drinking water quality report so instead of getting out your test tubes and litmus paper, you can simply compare their notes with these optimal parameters for making coffee.

Common Types of Drinking Water Treatment

Filtered – Water runs through a carbon filter. Some, but not all, of the minerals are filtered out. This system only works if the filter is replaced at recommended intervals.

Water Softener – Minimizes hardness ions. Calcium and magnesium ions are replaced through an exchange with sodium ions. This can make an okay cup of coffee, but additional carbon filtration is still a good idea. Deionized – A complete demineralization of the water using ion exchange. This does not make good water for coffee. Consider bottled water instead.

Reverse Osmosis – Uses a semipermeable membrane but they do not call it a filter per se. In certain situations minerals need to be re-introduced to balance the .pH. If this is your only option consider bottled water.

Distilled – The steam condensation from boiling water is collected and re-constituted as water. This water has no mineral content and is more expensive than deionization. It does not make good coffee.

Water, Water Everywhere

These principles apply to water used to craft a specialty cup of coffee, your coffee-making equipment has different needs however. If it is a mechanical device, scale build-up will remain a problem. Make time to descale on a regular basis whether you use an espresso machine, drip brewer or single-cup brewer. If your coffee-making device of choice is manual then make sure to keep it clean. Coffee oils and gunk can build up on the insides of an AeroPress just as it can with a French press. Clean water and a clean machine equal a clean cup of coffee. Give that Columbian microlot specialty coffee you brewed its due!


Samantha lives in West Seattle within walking distance of Puget Sound. She realized the importance of water after reading the book Dune in junior high school. Her brew method of choice at home is a Chemex. At work she uses a Technivorm Moccamaster KBG741. Yes, she always uses filtered water. Sometimes she even changes the filter in the pitcher.

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