The right coffee water - the coffee water guide

Reading time: 4 minutes. This article is a short blog post. You can find the full blog article here.

Since your coffee drink consists of over 90% water and less than 2% dissolved coffee particles, it is worth taking a closer look at the water. Even if it tastes good as drinking water in a glass, there are several criteria that make your tap water a good starting point for your coffee drink.

What should good coffee water be like?

In principle, coffee water should be soft, usually softer than what comes out of the tap. There are two values here:

• Total hardness = magnesium Mg+2 and calcium Ca2+
• Alkalinity = hydrogen carbonate = bicarbonate = HCO3-

For filter coffee, the best values are:

• Total hardness: 2 – 3 °dH
• Alkalinity: 1 – 2 °dH

For espresso, the best values are:

• Total hardness: 3 – 6 °dH
• Alkalinity: 2 – 4 °dH

Alkalinity is also often referred to as carbonate hardness, which is not strictly correct, but the term carbonate hardness has become established.

That sounds very complicated. We explain how you can achieve such good values here, as it is very unlikely you will get such soft water directly from your tap.

How good is my water at home?

There are several ways to measure water hardness. A conductivity meter, a ppm meter, and a drop test kit (the simplest option). In the latter case, 10ml of your water is filled into a tube and a few drops of test liquid are added. You count the drops, and as soon as the color changes, you know the water hardness. Alternatively, you can contact your local water supplier or visit their website.

How and what does a table water filter filter?

Tabletop filter devices are inexpensive and widespread. Water is poured in, and a maximum of 50% of the water is decarbonized. The other 50% simply runs through the device's activated carbon filter.

A quick calculation example: From the tap, we have drinking water with 16°dH total hardness and 12° dH alkalinity. After one pass through the water filter, the alkalinity is halved to 6° dH, but the total hardness only drops to 10° dH. Since this is still far from the perfect coffee water, we need a second pass.

After the second pass, the alkalinity is at 3°dH and the total hardness is at 7°dH. That is already good, but we only reach the perfect range with the third filtration (1.5° dH alkalinity and 5.5° dH total hardness).

In some cases, 3 or even more passes are necessary with tabletop filter devices. Quite elaborate!

The water filter with a fixed water connection

A luxury is a water filter with a fixed water connection, i.e., a permanently connected under-counter filter. It has a higher and more constant filter performance and filters the water directly to the desired value. Decarbonization takes place through ion exchange, which in turn changes the pH value of the water.

But is this luxury necessary? If you have hard water and prepare a lot of coffee, the purchase is worth it. 90% of machine defects are caused by water that is too hard. Considering the high purchase price of a good espresso machine, which you certainly want to use for a long time, you should think about such a filter system. It is generally cheaper to get an under-counter filter than to send your portafilter machine in for service once. In many cases, installation is simple, but it can also be carried out by professionals.

Another advantage is the reduced limescale content of the water, which you will also notice immediately in your kitchen, as white deposits will barely be found anymore.

Softening systems are not an alternative!

In some houses, the drinking water system is connected to a water softener. This softens the water through ion exchange (calcium and magnesium are replaced by sodium), but the alkalinity remains. This imbalance leads to the coffee tasting bland and boring during preparation, as the interplay of balanced acids and bitter notes does not work. One way out here is to go to the garden, as the garden hoses are usually not connected to the softener.

Concrete procedure on the way to your suitable coffee water

We are happy to help you achieve the right water hardness. This is how you proceed:

1. Measure your current water hardness with a drop test kit or ask your water supplier.
2. Estimate the amount of water you need per day.
3. Send the total hardness and alkalinity (carbonate hardness) along with the amount of water and your coffee beverage type to support@kaffeemacher.de
4. We will get back to you as soon as possible with a concrete recommendation on how you can achieve your target values.