Water filter cartridges and plug-in water filters tested

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

Importance of water for making coffee

Water plays a central role in coffee preparation. This is no surprise, as every coffee beverage consists of well over 90% water. Yet, for a long time, the primary focus was on protecting the machine, rather than on the water's impact on taste. Conveniently, the water that tastes good in coffee is also the water that protects the machine. We recommend the following water hardness levels.

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 comprehensive water article, we've covered the reasons and fundamentals of water chemistry in detail. We also provide tips on methods for testing water at home and the limitations of filtration. Another article is dedicated to filter water pads . We're currently working on a test of filter water pitchers.

Water filter cartridge test results

The following summary of the test results shows which water filter cartridges perform how well. 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 a second measurement, and then five more liters and a second measurement. Finally, 10 liters were pumped through the filter and measured again.

The measurements were taken using a droplet set for hardness measurement and a conductivity meter.

Results in German hardness = dH.

Special pump for measuring filter cartridges

Filter cartridges are usually located in the water tanks of coffee machines. The coffee machine pumps the water through the filter cartridge and then heats it. Measuring the already heated water would not have given us any usable results, as the heating process changes the water.

That's why we worked with an external pump that allowed us to regulate the flow rate to match the flow rate of the espresso machines.

Does the inlet water play a role?

The tests were conducted using water with an initial hardness of 13° German hardness and 11° German alkalinity. Filter performance was adequate even at water hardness levels up to 25° German hardness. The filters generally perform approximately up to the target value. However, filter life is significantly reduced when using harder water.

Are water filter cartridges recommended?

Three out of five filters delivered good results throughout the entire test. Their filter performance is even better than that of table water filters, for example. This is just a brief preview of the results of our table water filter test.

The Jura Claris filter really comes into its own after a few liters have run through the canister. Overall, however, it does a good job, producing great coffee while protecting the coffee machine.

The Brita Intenza also achieves good target values, especially at a flow rate of 5 liters or more. Conclusion: good for both coffee and machine, and also quite effective for filter coffee, as it tends to be on the softer side.

The BWT Best Cup water filter remains a bit too hard. It struggles to get going at first, and even after a while, the values ​​only barely reach the target range. Although a good hardness window is briefly reached after 6 liters of flow.

The Lelit MC747 is not a decarbonizer, but a desalinator. It removes magnesium and calcium from the water, but leaves the alkalinity intact. This protects the espresso machine, but doesn't prepare the water well enough to brew delicious coffee. The Lelit filter isn't well-suited for brewing coffee with a high sensory quality.

The Sage filter reaches full power after about 11 liters of flushing, 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 . However, the water's properties are also very suitable for brewing filter coffee.

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