Reading time: 4 minutes. This article is a short blog. You can find the detailed blog post here on our Swiss site.
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 tastes 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 must good coffee water be like?
Basically, coffee water should be soft, usually softer than what comes out of the tap. There are two measurements here:
- Total hardness = Magnesium Mg+2 and Calcium Ca2+
- Alkalinity = 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 accurate in strict terms, but carbonate hardness has become the established term.
This sounds quite complicated. We'll explain how you can achieve such good values here, 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 easiest 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's a color change, you know the water hardness. You can also contact your local water supplier or check 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 flows 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 cut in half 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 even more passes. Quite laborious!
The water filter with permanent water connection
A luxury is a water filter with a permanent water connection, i.e., a permanently installed under-sink filter. It has higher and more consistent filter performance and filters the water directly to the desired value. Decarbonization occurs through 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. 90% of machine defects are due to water that's too hard. Considering the expensive purchase price of a good espresso machine that you'll want to use for a long time, you should think about such a filter system. As a rule, it's cheaper to buy an under-sink filter than to send your portafilter machine in for servicing once. In many cases, installation is straightforward, but it can also be carried out by professionals.
Another advantage is the reduced limescale content of the water, which you'll notice immediately in your kitchen, as white deposits will be barely visible.
Desalination systems are not an alternative!
In some homes, 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 the alkalinity remains. This imbalance results in coffee preparation tasting bland and boring, as the interplay between balanced acids and bitter notes doesn't work. One way out here is to go out into the garden, as the water hoses are usually not connected to the desalination system.
Concrete procedure on the path to your suitable coffee water
We're happy to help you achieve the right water hardness at home. Here's how to proceed.
- You measure your existing water hardness with a drop test or ask your water supplier.
- You estimate the amount of water you need per day.
- You send the total hardness and alkalinity (carbonate hardness) along with the water amount and your type of coffee beverage to support@kaffeemacher.de
- We'll get back to you as soon as possible with a concrete recommendation on how you can achieve your target values.
