A Guide to Making the Best Water for Coffee – Epsom Salt and Baking Soda

Coffee Cup

How Important is it to Have the Right Water for Coffee?

Besides the freshness of beans being used, water is the most important aspect of a cup of coffee. In fact, the average cup of coffee is 98-99% water, with the remaining 1-2% being dissolved solids from the grounds and dregs.  As we noted in our cold brew guide, the right water is essential to a great tasting cup of coffee.  In addition, using water that is excessively hard in an espresso machine- or even a Keurig single-cup brewer- can cause internally damaging deposits to form, especially if descaling isn’t done regularly. Because water plays such a significant role in brewing coffee, it is important to be able to distinguish between good brewing water, and bad brewing water.

A good indicator of bad water is that which is discolored, smells, has particles floating around in it, and or a high chlorine content. However, just because the water looks and tastes fine doesn’t mean it would be great for coffee. Water hardness, which is the measure of the amount of magnesium and calcium present in any given sample, is an important consideration when considering the right brewing water.

Soft Water vs. Hard Water

To start, soft water contains no detectable amounts of calcium or magnesium, whereas hard water will have a detectable amount. Distilled water has no mineral content, but nearly all bottled and tap water do. With this in mind, mineral content is absolutely key to brewing a good cup of coffee- and this is because the minerals assist in bringing several flavor components out of the grounds themselves, and in addition, work to complement the components as well. Coffee brewed without these two key ingredients will be dull, and nearly flavorless. A simple way to demonstrate this is by brew coffee using distilled water, tasting it, and then brewing a cup using the water that is usually used.

However, not all hard water is created equally; some will be nearly soft, some just right, and some will taste like you’re licking a rock. It’s finding a way to get the perfect hardness that a lot of people can struggle with, and for that, there are a few different options.

Getting the Best Water for an Ideal Cup of Coffee

Filter pitchers and the like are decent options, but require filter changes, and the resulting water may not be perfect. Using bottled water can be hit or miss, as the mineral content can drastically vary by manufacturer.  Coffee shops often use a reverse osmosis system, which produces heavily filtered – essentially distilled water – then re-adds minerals back into it to produce just about perfect water; however, such a system comes at a very high price tag and is usually only used in commercial restaurants and cafes. But fear not, there is an incredibly easy and cost effective method to getting perfect, café quality, water in your home.

Making your Ideal Coffee Water at Home

To do this, you will need three ingredients:

Epsom salt (MgSO4, Magnesium Sulfate)

Baking Soda (NaHCO3, Sodium Bicarbonate)

Distilled Water (1 Gal)

All of these materials are available nearly everywhere and are incredibly inexpensive. When looking at Epsom salt, you just want the regular, no nonsense, plain variety; there is no need for any additional scents or ingredients like lavender or rose.

With these three ingredients, the process is fairly straight forward.

Get your one gallon (3.78 L) of distilled water, weigh out .75 grams of Epsom salt (0.15 teaspoons – close to an 1/8), and .25 grams of the baking soda (1/24 of a teaspoon).  Weighing the ingredients is best, because volumetric measuring can always potentially be off, as humidity and clumping can impact the measurement.

Then, combine all the ingredients, usually in the same jug that the water came in, and then mix it all around.  Even with mixing, the baking soda and epsom salt will take some time to fully dissolve and evenly distribute through the distilled water.

Storing the water in the fridge is a good option, but it can be stored on the countertop as well.

There are also companies that make packets of mineral mixtures to add to specified quantities of water, and if measuring out the quantities of minerals yourself seems like a bit much, this is an alternative. However, in the long run, you’ll end up paying significantly more by doing it this way. 

Jay Arr

Jay Arr is passionate about everything coffee. What began as a simple interest in the history, production, and brewing of coffee led him to a job as a barista at a national coffee chain. That’s not where Jay’s story with coffee ends, however. Roasting and brewing day in and out, he continued to gather knowledge about all things coffee.

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