Water filter cartridges and plug-in water filters tested

Many espresso machines and fully automatic coffee makers have plug-in functions for water filter cartridges. But are the plug-in filter cartridges actually any good? We tested 5 models and summarized the results in a video about plug-in water filters from BWT, Brita, Jura, Lelit and Sage.

Importance of water for coffee preparation

Water plays a central role in the preparation of coffee. This is no surprise, as every coffee drink consists of well over 90% water. Nevertheless, for a long time the focus was mainly on machine protection and less on the effects of water on taste. Conveniently, water that tastes good in coffee is also water that protects machines. We recommend the following hardness levels for water.

Perfect water for filter coffee:

Total hardness: 2 – 3 °dH

Alkalinity: 1 – 2 °dH

Perfect water for espresso:

Total hardness: 3 – 6 °dH

Alkalinity: 2 – 4 °dH

In our detailed water article we have thoroughly covered the reasons and fundamentals of water chemistry. We also provide tips on which methods can be used to test water at home and what the limitations of filtration are. Another article is devoted to filter water pads. We are currently working on a test of filter water jugs.

Water filter cartridge test results

The following summary of the test results shows how each water filter cartridge performed. For the test, the filter cartridges were first prepared as recommended by the manufacturer. Subsequently, one liter of water was first pumped through the filter and measured. This was followed by five more liters and another measurement, as well as five more liters and another measurement. Finally, 10 liters were pumped through the filter and measured again.

Measurements were made using a drop set for hardness measurement and a conductivity meter.

Results in German hardness = dH.

Special pump for measuring filter cartridges

Normally the filter cartridges are inserted into the water tanks of the coffee machines. The water is pumped through the filter cartridge by the coffee machine and then heated. Measuring the already heated water would not have given us usable results, as heating causes a change in the water.

That is why we used an external pump, which allowed us to regulate the flow rate so that it corresponded to the flow rate of espresso machines.

Does the input water matter?

The tests were conducted with water with an input hardness of 13° total hardness German hardness and 11° dH alkalinity. The filter performance was also appropriate at water hardness levels up to 25° German hardness. Generally, filters provide filtration performance up to the target value. However, the durability of the filters is significantly reduced when harder water is used.

Are water filter cartridges recommended?

3 out of 5 filters delivered good results throughout the test period. The filter performance is also better than, for example, with table water filters. This as a little preview of the results of our table water filter test.

The Jura Claris Filter shows its strength when several liters have run through the canister. Overall, it does a good job and enables good coffee while protecting the coffee machine.

The Brita Intenza also achieves good target values, especially from a flow of 5 liters onwards. Conclusion: good for coffee and machine, also quite strong for filter coffee because it tends to be in the soft range.

The BWT Best Cup Water Filter remains a bit too hard. At the beginning it doesn't get going and even after some flow the values only scratch the target range. Even though a good hardness window is briefly reached after 6 liters of flow.

The Lelit MC747 is not a water softener but a desalter. It removes magnesium and calcium from the water but leaves the alkalinity as is. This protects the espresso machine, but does not prepare the water well for brewing delicious coffee. The Lelit filter is not well suited for preparing sensorially high-quality coffee.

The Sage Filter gets going after about 11 liters flushed through and then brews good water on the rather softer side. This filter can be installed in espresso machines like the Sage Barista Pro or Sage Barista Touch. The water values are also very well suited for brewing filter coffee.