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Since your coffee beverage consists of over 90% water and less than 2% dissolved coffee particles, it's worth taking a closer look at the water. Even though it may taste good as drinking water in a glass, there are some criteria that make your drinking water a good starting point for your coffee beverage.
What makes good coffee water?
Basically, coffee water should be soft, usually softer than what comes out of the tap. There are two measurements for this:
- Total hardness = Magnesium Mg+2 and Calcium Ca2+
- Alkalinity = Bicarbonate = 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 often also referred to as carbonate hardness, which is not entirely correct in the strictest sense, but the term carbonate hardness has become established.
This already sounds quite complicated. We'll explain here how you can achieve such good values, since you most likely won't get such soft water 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 (the simplest method). 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 there is a color change, you know the water hardness. You also have the option of contacting your local water supplier or visiting their website.
How and what does the table water filter filter?
Table filter devices are inexpensive and widely available. Water is poured in and a maximum of 50% of the water is decarbonized. The other 50% simply passes through the activated carbon filter of the device.
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 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's 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, table filter devices require 3 or more passes. Quite time-consuming!
The water filter with fixed water connection
A luxury is a water filter with a fixed water connection, i.e. a permanently connected under-sink filter. It has a higher and more consistent filtration capacity and filters the water directly to the desired value. Decarbonization takes place through an ion exchange, which in turn changes the pH value of the water.
But is this luxury necessary? If you have hard water and make a lot of coffee, it's worth investing in one. 90% of machine defects are due to water that is too hard. Considering the expensive purchase price of a good espresso machine, which you certainly want to use for a long time, you should consider such a filter system. In most cases, it's cheaper to get an under-sink filter than to take your portafilter machine in for maintenance once. In many cases, installation is simple, but it can also be done by professionals.
Another advantage is the reduced lime content in the water, which you'll notice immediately in your kitchen as white deposits will barely be found.
Desalination systems are not an alternative!
In some houses, the drinking water system is connected to a desalination system. This softens the water through ion exchange (calcium and magnesium are replaced by sodium), but alkalinity remains. This imbalance in coffee preparation results in the coffee tasting bland and boring, because the interaction of balanced acids and bitter notes doesn't work. One way out here is to go to the garden, as water hoses are usually not connected to the desalination system.
Concrete procedure on your way to your ideal coffee water
We're happy to help you achieve the right water hardness for you. Here's how to proceed.
- Measure your current water hardness with a drop test or ask your water supplier.
- Estimate the amount of water you need per day.
- Send us the total hardness and alkalinity (carbonate hardness) along with the water quantity and your type of coffee beverage at support@kaffeemacher.de
- We'll get back to you as soon as possible with a specific recommendation on how to achieve your target values.
