Water hardness and tap water in Düren
Kreis Düren, Nordrhein-Westfalen · Postcode 52349, 52351, 52353, 52355
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 (17), at the waterworks
- Water hardness8.2 °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): Mittelwerte aus 10 Analysen (Juli 2025 bis Juni 2026) für den Versorgungsbereich Wasserbehälter Kirmesplatz, der laut Stadtwerke Düren Arnoldsweiler, Birkesdorf, Düren-Zentrum, Gürzenich, Hoven, Mariaweiler, Merken, Merzenich, Morschenich-Neu und Rölsdorf umfasst. Die Gesamthärte schwankte in diesem Zeitraum zwischen 4,9 und 10,4 °dH (weich bis mittel). Für andere Versorgungsbereiche veröffentlichen die Stadtwerke eigene Werte. Einzelprobe vom 25.03.2026 am Ablauf des Wasserbehälters Kirmesplatz (Wasserwerksausgang) – derselbe Versorgungsbereich wie die Härte-Mittelwerte. Hier nur die Spuren- und Schadstoffparameter, die in der Härteliste nicht enthalten sind; eine Einzelmessung kann vom Jahresmittel abweichen.
Background on household plumbing, not a measurement: in Düren, 58 % of buildings with living space were built before 1970, and a further 13 % 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 Düren
- Nitrate 17 mg/L – about 34 % of the limit of 50 mg/L and in the medium range – such values occur in catchments shaped by agriculture. Boiling does not reduce nitrate.
- PFAS (sum of PFAS-20) 8 ng/L – about 8 % 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 0.7 µg/L – unremarkable against a limit of 10 µg/L. In some regions uranium occurs naturally from the rock (geogenic).
- pH 7.96 – 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 Düren in everyday life
At 8.2 °dH, Düren 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 Düren 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 Düren 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 Düren |
|---|---|---|
| Sodium | 20 mg/l | 23.4 mg/l – above |
| Nitrate | 10 mg/l | 17 mg/l – above |
| Nitrite | 0.02 mg/l | below the detection limit (0.005 mg/l) – not above |
| Sulphate | 240 mg/l | 44 mg/l – not above |
| Fluoride | 0.7 mg/l | 0.09 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 (0.003 mg/l) – not above |
| Uranium | 0.002 mg/l | 0.0007 mg/l – not above |
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 Düren
Can you drink the tap water in Düren?
According to the verified values, yes: All tested parameters with a legal limit (17) 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 Düren?
The total hardness is 8.2 °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 Düren?
Yes, in measurable amounts: according to the published analysis by Stadtwerke Düren (SWD) (as of 25 March 2026), the sum of PFAS-20 is 0.008 µg/l – that is 8 % of the limit of 0.1 µg/l, which has applied since 12 January 2026. Even this sum of all 20 substances is below the limit of 0.02 µg/l that applies from 12 January 2028 to the sum of four of them (PFAS-4).
Do I need to filter my tap water in Düren?
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
- Wasserhärte nach § 9 WRMG und korrosionsrelevante Trinkwasserparameter – Versorgungsbereich Wasserbehälter Kirmesplatz, Analysezeitraum Juli 2025 bis Juni 2026 (Stadtwerke Düren GmbH) · SHA-256 of the evaluated file: a86e18ad80ac3f30…, checked on 3 October 2026
- Prüfbericht PB2026001554 – Wasserbehälter Kirmesplatz Ablauf (Wasserwerksausgang), Probenahme 25.03.2026 (Leitungspartner GmbH – Wasserlaboratorium Obermaubach (Tochter der Stadtwerke Düren)) · SHA-256 of the evaluated file: 951c9ceab37e1a51…, checked on 3 October 2026
Suggested citation: Trinkwassermonitor (2026): Tap water in Düren. Values according to the water supplier’s test report, sampling date June 2026; at the waterworks, not household plumbing. https://trinkwassermonitor.ink/en/tap-water/dueren/
JSON: /api/v1/evidence?city=dueren
Data as of: June 2026 · verified: 22 of 22 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 Düren. Retrieved from https://trinkwassermonitor.ink/en/tap-water/dueren/.”