Water filter cartridges and plug-in water filters tested

Many espresso machines and automatic coffee makers feature plug-in functions for water filter cartridges. But are these plug-in 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 Coffee Preparation

Water plays a central role in preparing coffee. This is no surprise, as every coffee beverage consists of well over 90% water. Nevertheless, for a long time, the focus was primarily on machine protection and less on the impact of water on taste. Conveniently, water that tastes good in coffee also 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 thoroughly discussed the reasons and basics of water chemistry. We also provide tips on how to test water at home and the limits of filtration. Another article is dedicated to water filter 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 well each water filter cartridge performs. For the test, the filter cartridges were first prepared as recommended by the manufacturer. Then, one liter of water was pumped through the filter and measured. This was followed by five more liters and another measurement, as well as five additional liters and another measurement. Finally, 10 liters were pumped through the filter and measured again.

Measurements were taken using a droplet test kit for hardness measurement and a conductivity meter.

Results in German Hardness = dH.

Special Pump for Measuring Filter Cartridges

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

Therefore, we worked with an external pump that allowed us to regulate the flow to match the flow rate of espresso machines.

Does the Input Water Play a Role?

The tests were conducted with input water having a total hardness of 13° German Hardness and 11° dH alkalinity. The filtering performance was also consistent for water hardnesses up to 25° German Hardness. Generally, the filters perform their filtering function approximately 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 entire test. The filtering performance is also better than, for example, with tabletop water filters. This is a small preview of the results of our tabletop water filter test.

The Jura Claris Filter shows its strength after a few liters have passed through the canister. It generally does a good job and allows for good coffee while also protecting the coffee machine.

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

The BWT Best Cup Water Filter remains a bit too hard. It doesn't get going initially, 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 decalcifier but a desalter. It removes magnesium and calcium from the water but leaves the alkalinity. This protects the espresso machine, but it 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 have been flushed through, and then brews good water on the 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.

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