Water is very important for the taste of coffee

Water, more precisely its composition, greatly affects the taste of coffee.

In this article, we will look at:

  • Do only professionals recognize the different composition of water?
  • What to do to make your coffee taste the same as in the Roastery.
  • Simple but also more complex approaches to the perfect coffee water at home.
  • How about filters and filter kettles.
  • Water measurement.

I often come across the opinion: "I'm not such an expert to recognize it." Unfortunately, almost everyone is. So this article is very likely to apply to you as well. 

What is it all about?

In water, we need to look at two things: 

Total hardness and carbonate hardness of water. 

Total hardness

is caused mainly by the anions Calcium and Magnesium Ca and Mg. These minerals are directly responsible for extracting "the good stuff" from coffee. If there are too few of them, the coffee will be underextracted. Thin, watery. If there are too many of them, the coffee will be too extracted and this will manifest itself as, for example, too bitter. 

Carbonate hardness

Caused by HCO3- also called as buffer or alkalinity. It is the ability of water to absorb acid (coffee is acid) without changing the pH of water. If the buffer is low, the water becomes acid relatively quickly. The coffee will taste too sharp-sour. If, on the other hand, there is a lot of it, then the coffee will taste dry, chalky. The value of carbonate hardness at which coffee tastes excellent acquires values from a relatively narrow range. The overall hardness can have significantly more fluctuations and the coffee will be great. 

There are other substances in the water, but their direct effect on the taste of the prepared coffee has not yet been proven. 

Coffee water like in a Roastery?

We have some basic options:

  • You are lucky and your water is suitable for making coffee as it is. It is easy to verify. They will do an analysis of the total and carbonate hardness for about 5 euros.
  • Bottled water. The waters available in Slovakia are almost all unsuitable for making coffee. The exception is ARO water. Can be bought in the METRO in a 5l bottle. It is probably the cheapest water in general. The second is Dobrá Voda. You can buy it in Coop, Kaufland... Both of these waters are fine, but not perfect. They have a little more HCO3- than they should have. 
  • You can prepare the water yourself. 

Home preparation of perfect coffee water

You will need 

    • Clean water. H20. No other soluble or insoluble matter
    • Magnesium. Magnesium can be easily and cheaply obtained in the form of magnesium sulphate (MgSO4). It is often referred to as the Epsom salt
    • HCO3-. Easiest to get married like Baking soda = Soda bicarbona = sodium bicarbonate, NaHCO3

Pure water (H2O): Can be bought e.g. in the pharmacy. Those that are at gas stations are distilled, but they are not suitable for food purposes, so it can easily happen that they will contain something harmful to health. 

You can easily prepare distilled water at home. You need a distiller for that. The distiller can be bought relatively cheaply if you know where. We took over the topic in the Facebook group Coffia Public Group Tomáš Polák can help with the distiller in the group.

A convenient but expensive way is to use reverse osmosis (RO). RO can filter almost everything from water and create pure H2O, which is not suitable for drinking without minerals. Therefore, part of the water passes through more common filters and is mixed into RO water. For our needs, it is necessary to disconnect this part and use only clean RO water. 

Magnesium: I write above that the overall hardness is caused by magnesium and calcium. Both of these substances are responsible for extracting soluble substances from the coffee beans and only thanks to them is proper extraction possible. However, recent research has confirmed that coffee tastes better if it has more magnesium in water than calcium. And the bigger the ratio, the better. That is why we very often come across recipes that simply omit calcium. 

The recipe was published by the guys from BaristaHustle on their website.

Source: BaristaHustle

Approach. In the beginning, we will create concentrates, which we will later use in the production of our perfect coffee water. 

Buffer concentrate (alkalinity) concentrate is prepared by dissolving 1.60 g of bicarbonate of sodium in 1 liter of H 2 O. 

Prepare the magnesium concentrate by dissolving 2.45 g of Epsom salt in 1 liter of H2O.


  • 40.1g Buffer concentrate
  • 68.6g Magnesium Concentrate
  • 891.3g H20 (distilled or RO water)

Scott Rao Recipe

  • 50.1g Buffer concentrate
  • 75.7g Magnesium concentrate
  • 874.2g H2O

As you can see, preparing your own water is not as difficult at all as it might seem. You just need to be accurate and weigh at least 0.01g. You can find other recipes at BaristaHustle, for example. If you manage to create your own recipe, we will be happy if you share it on our fb group. 

Filters and filter kettles

There are various filters and filter kettles. Can you use them successfully? It depends to a large extent on the composition of your raw water (what flows from your tap). For example, if your raw water is relatively close, the filters may be successful. But if you do not have a favorable ratio between the individual minerals, it is likely that even the filter will not help you. For example, you can't tell the filter to reduce the overall hardness just a little, but it reduces the alkalinity intensely and vice versa. If you do not use the filter for a while, the water in it will hold a lot of minerals (hypermineralization) than when water just flows through the filter. If you let a lot of water flow, the filter "gets tired" and supplies less minerals than usual. It is ideal if you can borrow the filter somewhere before the purchase and have it analyzed. I suggest 3 samples.

  1. When water has not been used for a long time
  2. When the amount flowed out is larger than the capacity of the filter (its volume)
  3. When the water flowed through the filter longer. For example, you need to fill a larger coffee maker.

Each sample will cost about 5 euros, but you will get an idea of how the filter can fit with your raw water. 

 Measuring at home

Coffee for home can be measured using titration drops. Titration drops from BWT or Brita work on German degrees. One solution is for total hardness and the other for alkalinity. 

It works by putting the exact amount of tested water into the measuring cup according to the manufacturer's instructions. We drip one drop into it and mix the measuring cups in a circular motion. Add another drop and mix. This is continued until the test sample changes color. For example, we have a test solution green and the first drop turns the water to pink. It is not until the sixth drop that the test sample turns deep green. This tells us that the tested water has 6 degrees of hardness.

I like water when the alkalinity is one degree of German hardness and the total hardness is 6 degrees.

TDS meter

Total Disolved solids meter is a device that can use conductivity to measure how many soluble substances are in a test sample. They are usually measured in ppm (parts per million). However, the device will not tell you what the composition is. So one water with ppm 156 may be excellent for coffee, another with ppm +156 absolutely unsuitable. However, if you know in advance what you are giving there and in what proportion, then TDS is good for verifying that an error has not occurred somewhere. For example, if you are testing distilled water, the TDS meter should read somewhere between 4ppm and 12ppm. If it shows you significantly more, then your water is not clear. But she will not tell you what is dissolved in her. 

Transfers between different units


Perfect water for making coffee 

should have the following values:




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