Water filter cartridges and plug-in water filters tested

Many espresso machines and fully automatic coffee machines feature plug-in connections for water filter cartridges. But are these pluggable filter cartridges 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.

The importance of water for preparing coffee

Water plays a central role in preparing coffee. This comes as no surprise, since every coffee beverage consists of well over 90% water. Nevertheless, for a long time, the focus was primarily on machine protection rather than the impact 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 covered the reasons and basics of water chemistry in depth. There, we also provide tips on methods for testing water at home and what the limits of filtration are. Another article is dedicated to filter water pads. We are currently working on a test of water filter pitchers.

Water filter cartridge test results

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

Measurements were taken using a drop test kit for hardness as well as a conductivity meter.

Results in German degrees of hardness = dH.

Special pump for measuring filter cartridges

Normally, filter cartridges are inserted into the water tanks of coffee machines. The water is pumped by the coffee machine through the filter cartridge and then heated. Measuring the water after it has been heated would not have given us usable results, as heating causes changes to the water.

Therefore, we used an external pump, where we could regulate the flow rate to match the flow speed of espresso machines.

Does the source water matter?

The tests were conducted with water having an inlet hardness of 13° total German hardness and 11° dH alkalinity. The filter performance was consistent even with water hardness levels up to 25° German hardness. In principle, the filters provide their filtration performance up to the target value. However, the lifespan 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 entire test process. The filtration performance is also better than, for example, that of tabletop water filters. Just a small preview of the results of our tabletop water filter test.

The Jura Claris filter plays to its strengths once a few liters have passed through the canister. Overall, however, it does a good job, enables good coffee, and protects the coffee machine at the same time.

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

The BWT Best Cup water filter remains slightly too hard. It is slow to get going at the beginning, and even after some flow, the values only just scratch the target range, even if a good hardness window is briefly reached after 6 liters of flow.

The Lelit MC747 is not a decarbonizer but a demineralizer. 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 picks up speed after about 11 liters flushed through and then brews good water on the softer side. This filter can be installed in espresso machines such as the Sage Barista Pro or Sage Barista Touch. The water values are also very well-suited for brewing filter coffee.

If you would like to find out more about the perfect water for coffee, you can find all our articles on the topic here.