Water hardness and tap water in Aachen
Aachen, Nordrhein-Westfalen · Postcode 52062, 52064, 52066, 52068, 52070, 52072 …
This page is a translation of the German version; the German page is authoritative. German version · Report a translation error
- Limits of the Drinking Water OrdinancemetAll tested parameters (20), at the waterworks
- Water hardness3.7 °dH, softNo legal limit, only a range
- Data coverageCore parameters: 7 of 7Score based on complete data
Verified drinking-water values
Note from the test report (in the German original): STAWAG · Jahresauswertung 2025 des Wasserlabors der WAG für das Trinkwasser aus der Aufbereitungsanlage Roetgen (Talsperrenwasser, Probenahmestelle „Roetgen TW Netzeinspeisung“). Die Werte sind Jahresmittelwerte 2025 aus 12 bis 365 Proben je Parameter, deshalb ist nur das Jahr angegeben. Laut Wasserhärte-Finder der STAWAG liegen 1.075 der 1.354 Aachener Straßen im Härtebereich 1 (weich), zu dem dieses Wasser gehört. 279 Straßen, u. a. in der Innenstadt, liegen im Härtebereich 2 (mittel, laut STAWAG-Übersicht 6,0 bis 14,0 °dH), der auch aus Grundwasser versorgt wird; dort kann im Ausnahmefall ebenfalls weiches Wasser ankommen. Welcher Bereich für Ihre Adresse gilt, zeigt der Wasserhärte-Finder auf stawag.de.
Background on household plumbing, not a measurement: in Aachen, 57 % of buildings with living space were built before 1970, and a further 14 % between 1970 and 1979 (Zensus 2022, Statistisches Bundesamt, dl-de/by-2-0). (Zensus 2022) According to the German Environment Agency (Umweltbundesamt), lead pipes exist at most in houses built before 1973 – and by no means in all of them. Whether there are any in your house is known to the owner or a plumber. (UBA)
What the values mean for Aachen
- PFAS (sum of PFAS-20) 3 ng/L – about 3 % of the limit of 100 ng/L (since 12 January 2026).
- Lead – not detectable at the waterworks. Lead gets into the water almost only through old lead pipes in household plumbing, not via the supplier.
- Uranium – not detectable at the waterworks (limit 10 µg/L).
- pH 8.95 – within the range of the Drinking Water Ordinance (6.5 to 9.5). The pH determines how corrosive the water is in household plumbing.
Water hardness in Aachen in everyday life
At 3.7 °dH, Aachen is in the hardness range “soft” (soft: below 8.4 °dH, medium: 8.4–14 °dH, hard: above 14 °dH).
- Dose detergent for the hardness range “soft” – the lowest amount on the pack.
- Limescale deposits are rare; kettles and coffee machines only need descaling every few months.
- At this hardness you do not need limescale protection or a water softener.
Baby food and low sodium: tap water in Aachen next to the bottled-water thresholds
Bottled water may only be labelled “suitable for preparing infant food” („geeignet für die Zubereitung von Säuglingsnahrung“) if it keeps to the maximum levels of the German Mineral and Table Water Ordinance (Mineral- und Tafelwasser-Verordnung, Annex 6). Here the published values for Aachen are shown next to them, each substance on its own. This is a comparison with labelling thresholds for bottled water, not a statement on whether your tap water is suitable for baby food. (Min/TafelWV, Anlage 6)
| Substance | Maximum level | Value in Aachen |
|---|---|---|
| Sodium | 20 mg/l | 13 mg/l – not above |
| Nitrate | 10 mg/l | below the detection limit (7 mg/l) – not above |
| Nitrite | 0.02 mg/l | below the detection limit (0.01 mg/l) – not above |
| Sulphate | 240 mg/l | 24 mg/l – not above |
| Fluoride | 0.7 mg/l | below the detection limit (0.6 mg/l) – not above |
| Manganese | 0.05 mg/l | below the detection limit (0.005 mg/l) – not above |
| Arsenic | 0.005 mg/l | below the detection limit (0.0005 mg/l) – not above |
| Uranium | 0.002 mg/l | below the detection limit (0.0002 mg/l) – not above |
Against the other thresholds of Annex 6, the water would qualify as: low in sodium (“suitable for a low-sodium diet”) (Sodium 13 mg/l, threshold below 20 mg/l).
For context: the German Environment Agency (Umweltbundesamt) considers preparing baby food with bottled water carrying this label necessary only in rare cases, for example when tap water is temporarily allowed to contain more than 50 mg/l nitrate. (UBA 2016, p. 59) Water from lead pipes in the house is always unsuitable for infants. (UBA 2020, p. 16) The values apply at the waterworks. Questions about baby food are answered by your midwife, your paediatrician and the health office (Gesundheitsamt).
Frequently asked questions about tap water in Aachen
Can you drink the tap water in Aachen?
According to the verified values, yes: All tested parameters with a legal limit (20) meet the limits set by the German Drinking Water Ordinance (TrinkwV). WaterScore: 100 out of 100 (data coverage: 7 of 7 core parameters). This applies to the water from the waterworks – restrictions can only arise from old household plumbing.
How hard is the water in Aachen?
The total hardness is 3.7 °dH – hardness range “soft”. Dose detergent for the hardness range “soft” – the lowest amount on the pack.
Is there PFAS in the tap water in Aachen?
Yes, in measurable amounts: according to the published analysis by STAWAG (as of 2025), the sum of PFAS-20 is 0.003 (middle of the range given by the supplier) µg/l – that is 3 % of the limit of 0.1 µg/l, which has applied since 12 January 2026.
Do I need to filter my tap water in Aachen?
Based on the verified supplier values, a filter is not necessary. It can make sense if you do not like the taste. If you suspect lead pipes in an old building, a filter does not help; a laboratory analysis at the tap does – that is a question of the household plumbing, not of the water leaving the works.
WaterScore
- Total100 / 100
- Chemical safety100 / 100
- Heavy metals100 / 100
- PFAS100 / 100
- Nutrients100 / 100
- General parameters100 / 100
- Data timeliness100 / 100
- Data quality100 / 100
Data coverage: 7 of 7 core parameters. Missing parameters are neither estimated nor counted as harmless: the score is based only on the values available. It is not a health assessment and says nothing about the water beyond the service connection. Methodology v3: how we calculate the WaterScore.
Evidence: cite and check
- Trinkwasseranalyse aus der Aufbereitungsanlage Roetgen (Stand 2025) – Roetgen TW Netzeinspeisung, Jahresauswertung 01.01.–31.12.2025 (WAG Wassergewinnungs- und -aufbereitungsgesellschaft Nordeifel mbH, Wasserlabor (für die STAWAG)) · SHA-256 of the evaluated file: c1a401a48d28dd4c…, checked on 3 October 2026
Suggested citation: Trinkwassermonitor (2025): Tap water in Aachen. Values according to the water supplier’s test report, sampling date 2025; at the waterworks, not household plumbing. https://trinkwassermonitor.ink/en/tap-water/aachen/
JSON: /api/v1/evidence?city=aachen
Data as of: 2025 · verified: 25 of 25 evaluated parameters.
This page shows only verified test data with sources, or states explicitly where data is missing (no estimated values). Cite as: “Trinkwassermonitor (2026). Tap water in Aachen. Retrieved from https://trinkwassermonitor.ink/en/tap-water/aachen/.”