What is the best water to prepare coffee?

It has been a long time since I should have talked about the water we use to prepare coffee since this topic is very important. However, it is an issue we tend to overlook, so if you want to improve the coffees you prepare, this article will greatly help you.

Water is one of the two ingredients used to prepare coffee, accounting for almost 98% of the beverage. So, not only should we be concerned about having top-quality coffee beans but also water that is up to the task.

If, despite using coffee beans of the highest quality, with the correct equipment and a safe recipe, you do not obtain a delicious coffee, it could be that the water you are using is failing.

The importance of water in the preparation of coffee

Water works as a solvent, dissolving the soluble material of roasted and ground coffee in the process known as extraction. Depending on the composition of the water, this extraction will be less or more.

  • When an under-extraction occurs, we do not obtain all the exquisite flavors this coffee offers.
  • On the other hand, if over-extraction occurs, we will extract some undesired flavors, so we do not want to extract too much, either.

But water not only influences the extraction; water with a strong chlorine taste will hurt the final beverage. Or water that is too hard will damage all our equipment by accumulating limescale residues on the internal components of our expensive coffee machines.

What type of water should I use to prepare my coffee?

Depending on where you live, the quality of the tap water will vary a lot.

  • In cases where the water is soft, it will be easy to treat it; by placing a basic filter, you will eliminate all the chlorine and odors, all without affecting the mineral composition.
  • In other cases, the water is very hard and more complicated to treat; with a common filter, it is no longer enough, and it is required to purify it with a system such as reverse osmosis. Although we must then remineralize it since we need a certain amount of minerals to obtain a good coffee extraction.

A very popular but not recommended solution is to buy bottled water. This is not only harmful to the environment (plastic waste), but sometimes it is difficult to get a brand of water within the ideal composition we would like for our coffee.

If you want to take your coffee to another level, keep reading because today, I will teach you how to prepare your water with the perfect composition. It is very simple and only requires three ingredients.

The Specialty Coffee Association, or SCA, tells us the composition that the water should have for preparing coffee, both in an acceptable range and a specific target. And the recipe that I share with you here is the one recommended by Scott Rao:

How to prepare your own water for making coffee

As I said before if your local tap water is soft and of good quality, you will have no more than filtering it to achieve great coffee. However, this water brewing recipe will be ideal for making the perfect coffee.

Ingredients of the perfect coffee water recipe

These ingredients are very easy to obtain. You can find distilled water in markets or gas stations, baking soda in health food stores or pharmacies, and Epsom salt in health food stores, or you can directly search for everything in online stores such as Amazon.

Ingredients for the preparation of water
Ingredients for the preparation of water

Utensils needed for our coffee water recipe

We will make two concentrates, which we will then add in different parts to form our final water. For this, we need two 1-liter bottles filled with distilled water and a scale measuring 0.1 grams.

  • We add 1.68 grams of sodium bicarbonate in one bottle, forming our alkalinity regulator.
  • In the other bottle, we add 2.45 grams of Epsom salts, the magnesium that will make our hardness.

We stir both bottles well to mix these concentrated solutions and prepare our final water.

Step by step to prepare the perfect coffee water

  1. From a 5-liter bottle of distilled water, we are going to take out half a liter of water to be able to add our concentrates.
  2. Once we have 4.5 liters, we will add (according to Scott Rao’s recipe) 9 ounces of the alkalinity solution and 13 ounces of the hardness solution.
  3. After stirring well, we now have our 5-liter drum of water with a mineral composition perfect for coffee extraction.

When we taste it, we feel an interesting contrast with the filtered water we use at home.

Comparison of the above recipe with other supermarket waters

When you go to the supermarket to buy bottled water, these usually have their mineral composition detailed on the label. It is very important that you pay attention to which water you buy as there are big differences between them.

To give you a rough guide on what to look for, there are two main minerals calcium and magnesium. An acceptable range of calcium would be between 30 and 50 milligrams per liter and magnesium between 15 and 30 milligrams per liter.

Compare different waters to use the best one in your coffee maker

When you buy bottled water, one thinks they all taste the same; however, this is far from true. To write this article, I bought 5 bottles of water from different brands and did a small tasting to compare them with each other. All of them ranged between 30-50ml of calcium and 15-30ml of magnesium per liter.

I recommend you do this experiment at home, as you will be surprised by the results. Of the five water brands, two were very good, one was very bad, and two others did not stand out for any attribute. In other words, less than 50% of the brands I find in my supermarket can be considered good for brewing coffee.

After tasting just the water, I prepared coffee with each of them. Although the taste of the coffee overshadowed the differences, the two brands I liked also stood out in the coffee. It seemed as if the coffee flavors stood out more with these two water brands.


I hope this exercise helps you to choose better water to put in your espresso machine or to prepare your recipe. You will obtain a much tastier coffee and take care of your machine, ensuring that it will last a long time without being damaged inside.

If you want to prepare more or less water, simply use the same proportion of concentrate for the amount of distilled water. And if you are traveling or need to buy water for a one-time purchase at a supermarket, I recommend you take a close look at the proportions of calcium and magnesium per liter.

Written by Pablo Barrantes Nevado
I am Pablo Barrantes, a coffee lover. I decided to start this website to solve all the doubts that arise every day when preparing our favorite drink: coffee. I am an industrial engineer by profession, but I have worked in coffee shops for many years, where I have learned all the secrets about coffee machines and coffee. My passion for coffee has led me to investigate and study beyond the obvious, and thanks to this, I can offer solutions and give news about coffee and coffee makers. I hope you enjoy reading as much as I research, document and write here.

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