Water hardness and tap water in Konstanz
Landkreis Konstanz, Baden-Württemberg · Postcode 78462, 78464, 78465, 78467
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 (12), at the waterworks
- Water hardness8.96 °dH, mediumNo legal limit, only a range
- Data coverageCore parameters: 3 of 7Score provisional
Verified drinking-water values
Note from the test report (in the German original): Probenahmeort laut Prüfbericht: Seewasserwerk, Reinwasserpumpe 'Friedrich III / nach Aufbereitung' (aufbereitetes, noch unvermischtes Wasser am Werksausgang, nicht an einem Kundenzapfhahn). Probenahme 03.02.2025, digital signiert 07.03.2025, Eurofins Institut Jäger GmbH (DAkkS-akkreditiert). Der Bericht deckt nur TrinkwV-Parametergruppe B ab; eine mikrobiologische Gruppe-A-Untersuchung sowie Trihalomethane, Blei, Kupfer und Arsen sind darin nicht enthalten. Für pH-Wert und Leitfähigkeit liegen zwei Messungen vor (Vor-Ort: pH 8,14/327 µS/cm; Labor nach Transport: pH 8,07/333 µS/cm) – hier wurden die offiziellen Laborwerte übernommen. Eine live aktualisierte Kurzübersicht auf stadtwerke-konstanz.de zeigt mit 9,17 °dH/pH 7,8 leicht abweichende Werte gegenüber diesem Prüfbericht (8,96 °dH/pH 8,07) – vermutlich eine andere Probenahmerunde, zur menschlichen Prüfung markiert.
Background on household plumbing, not a measurement: in Konstanz, 54 % 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 Konstanz
- Nitrate 3.4 mg/L – about 7 % of the limit of 50 mg/L and in the unremarkable range. Boiling does not reduce nitrate.
- PFAS (sum of PFAS-20) 2.9 ng/L – about 3 % of the limit of 100 ng/L (since 12 January 2026).
- Uranium 1.1 µg/L – unremarkable against a limit of 10 µg/L. In some regions uranium occurs naturally from the rock (geogenic).
- pH 8.07 – 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 Konstanz in everyday life
At 8.96 °dH, Konstanz is in the hardness range “medium” (soft: below 8.4 °dH, medium: 8.4–14 °dH, hard: above 14 °dH).
- Dose detergent for the hardness range “medium”.
- As a rule of thumb, descale the kettle about every four to six weeks and the coffee machine as the manufacturer recommends.
- A limescale protection device is not a must at medium hardness; regular descaling is often enough.
Baby food and low sodium: tap water in Konstanz 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 Konstanz 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 Konstanz |
|---|---|---|
| Sodium | 20 mg/l | 5.6 mg/l – not above |
| Nitrate | 10 mg/l | 3.4 mg/l – not above |
| Nitrite | 0.02 mg/l | not in the report |
| Sulphate | 240 mg/l | 34 mg/l – not above |
| Fluoride | 0.7 mg/l | below the detection limit (0.15 mg/l) – not above |
| Manganese | 0.05 mg/l | below the detection limit (0.001 mg/l) – not above |
| Arsenic | 0.005 mg/l | not in the report |
| Uranium | 0.002 mg/l | 0.0011 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 5.6 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 Konstanz
Can you drink the tap water in Konstanz?
According to the verified values, yes: All tested parameters with a legal limit (12) meet the limits set by the German Drinking Water Ordinance (TrinkwV). WaterScore (provisional): 97.9 out of 100 – the test report contains only 3 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 Konstanz?
The total hardness is 8.96 °dH – hardness range “medium”. Dose detergent for the hardness range “medium”.
Is there PFAS in the tap water in Konstanz?
Yes, in measurable amounts: according to the published analysis by Stadtwerke Konstanz (as of 3 February 2025), the sum of PFAS-20 is 0.0029 µg/l – that is 3 % 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 Konstanz?
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
- Total (provisional)97.9 / 100
- Chemical safety100 / 100
- Heavy metals100 / 100
- PFAS100 / 100
- Nutrients100 / 100
- General parameters100 / 100
- Data timeliness85.8 / 100
- Data quality100 / 100
Data coverage: 3 of 7 core parameters. Not in the test report: Nitrite, Lead, Copper and Arsenic. Missing parameters are neither estimated nor counted as harmless: the score is based only on the values available and is therefore provisional. 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
- Prüfbericht zu Auftrag 22503391 – Untersuchung gemäß TrinkwV Parameter Gruppe B (Prüfberichtsnummer AR-25-R9-001455-01) (Eurofins Institut Jäger GmbH (im Auftrag der Stadtwerke Konstanz GmbH)) · SHA-256 of the evaluated file: d618255bddf0aa01…, checked on 3 October 2026
Suggested citation: Trinkwassermonitor (2025): Tap water in Konstanz. Values according to the water supplier’s test report, sampling date 3 February 2025; at the waterworks, not household plumbing. https://trinkwassermonitor.ink/en/tap-water/konstanz/
JSON: /api/v1/evidence?city=konstanz
Data as of: 3 February 2025 · verified: 20 of 20 evaluated parameters. (older than twelve months – under § 46 TrinkwV your supplier must publish current values online)
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 Konstanz. Retrieved from https://trinkwassermonitor.ink/en/tap-water/konstanz/.”