Does tap water contain minerals? What's in it and what a faucet filter changes
Yes, German tap water generally contains minerals. Calcium, magnesium, sodium, potassium and bicarbonate dissolve from the ground through which the water flows on its way to extraction, which is exactly why mineral content varies noticeably from region to region. There is no blanket answer to how much of these minerals actually ends up in your glass, but every water supplier publishes reliable figures for its network. A faucet-mounted activated carbon filter does not change this mineral content: according to the product information, it is designed to address chlorine taste, odor and sediment, not dissolved minerals.
- Typical minerals: Calcium, magnesium, sodium, potassium and bicarbonate are among the usual dissolved components of German tap water, in varying amounts from region to region.
- Finding your own values: Your local water supplier publishes test results for its service area, usually online or upon request.
- Comparison with mineral water: Mineral water is not automatically richer in minerals than tap water; both vary depending on the source or region.
- Faucet filter: An activated carbon filter targets taste, odor and particles, not dissolved minerals or the water's hardness itself.
What minerals are in German tap water?
Before drinking water comes out of the tap, it has usually traveled a long way through layers of soil and rock, and it is there that it picks up the minerals that later shape its taste and composition. Calcium and magnesium primarily determine water hardness, bicarbonate buffers the pH, and sodium and potassium are usually present in smaller amounts. Because the geological makeup varies from region to region, the amounts of these substances also vary considerably. This explains why tap water from two neighboring towns can taste different, even when both are perfectly safe to drink (German Environment Agency).
According to the German Environment Agency, more than 99% of quality requirements for German drinking water were met between 2020 and 2022, a figure that primarily concerns pollutants, germs and similar safety parameters. On its own, this figure says little about mineral content, since both water low in minerals and water rich in minerals can easily meet the regulations. So if you want to know whether your own water is soft or hard, and how much calcium or magnesium it actually contains, you need to go beyond simply checking whether it meets the limit values.
Where to find the actual values for your own water
The local water supplier is responsible for water quality up to the property's service connection, and that responsibility includes a duty to publish the information. In practice, this means the latest test results for your service area are either available directly on the supplier's website or provided upon request, often with a water-hardness classification. If you have already read our in-depth article on TDS values and measuring devices, you know the difference between a general TDS reading and the detailed mineral list in an official analysis: the latter shows individual substances rather than just a total for dissolved solids.
Example: reading an actual drinking water analysis
Berliner Wasserbetriebe reports, among other values, the following for its network (as of 2025): calcium approximately 116 mg/L, magnesium approximately 11 mg/L, sodium approximately 37 mg/L, potassium approximately 5 mg/L and bicarbonate approximately 262 mg/L (Berliner Wasserbetriebe). These figures illustrate how such an analysis is structured and what ranges are realistic for individual minerals; however, they apply only to the Berlin network and cannot be applied to every other address in Germany. For your own home, your own supplier remains the authoritative source, even though the basic approach to analysis is similar everywhere.
Tap water compared with mineral water
The common assumption that mineral water automatically contains more minerals than tap water does not stand up to closer scrutiny. Stiftung Warentest tested 52 mineral waters and found that around half contained less than 500 mg of minerals per liter, meaning they were by no means all rich in minerals (Stiftung Warentest). At the same time, some tap water reaches or exceeds this value, depending on the region it comes from, and therefore contains more dissolved minerals than some bottled water on supermarket shelves (DAK).
There is no overall winner: both types of water vary considerably from source to source or place to place, and the question of which water provides more minerals can only be answered by looking at the specific values for each, not by relying on the categories “tap water” or “mineral water” themselves. If you are interested in other aspects of water quality in Europe, find out more in our overview of other substances in European tap water.
What a faucet-mounted activated carbon filter actually changes
A faucet-mounted activated carbon filter like this one works on a different principle from a mineral water analysis. According to the product page, the four-layer cartridge combines a coconut shell activated carbon block, a silver-plated layer, a layer that prevents limescale buildup inside the device itself, and a KDF medium. It is therefore primarily designed to target chlorine taste, odor, sediment and rust, as well as lead, heavy metals and PFAS, according to the manufacturer. These reduction claims come from the manufacturer's product page and are not independently verified certifications or percentage figures, even though they accurately describe how the cartridge works.
Another statement on the same product page is key to answering the original question: it explicitly says that naturally occurring minerals are retained and that the filter does not reduce dissolved solids, or the TDS value. The cartridge's anti-limescale layer is intended to reduce limescale buildup inside the filter housing itself so that the cartridge remains functional for longer; this is different from softening the water flowing through it, and the two effects should not be confused. In other words, anyone concerned about the mineral content of their water will not get an answer from this type of filter, because it is not designed for that purpose.
What changes and what stays the same: a quick overview
The following overview summarizes what the four-layer activated carbon filter changes according to the product information and what it leaves untouched:
| Changes according to the product information | Remains unchanged according to the product information |
|---|---|
| Chlorine taste and odor | Dissolved minerals (calcium, magnesium, sodium, potassium, bicarbonate) |
| Sediment, sand and suspended particles | Total dissolved solids (TDS) |
| Limescale buildup inside the filter housing | The hardness of the water flowing through it |
For everyday use, the manufacturer recommends replacing the cartridge after three months or 1,211 liters, whichever comes first. The filter fits round faucets with an external thread of 20 to 22 mm or an internal thread of 24 mm using the included adapters; it is not designed for swivel-spout faucets, showerheads or touchless faucets, so it is worth checking your faucet's thread before buying. If you are looking for a larger solution for your whole home instead, find out more in our guide to whole-house water filtration systems.
In summary
German tap water generally contains minerals, and the most reliable way to find out the exact amount is to check the published analysis from your own water supplier, not to make a general comparison with mineral water. If you dislike the taste or odor of chlorine, or sediment in your tap water, that is a clear concern that a faucet-mounted activated carbon filter addresses according to the product information. If, on the other hand, you want to know how many minerals are in your own water, you still need to rely on your water supplier's analysis, because no filter of this type can answer that question. Find more background on water quality and hydrogen water in the Hydrion blog.