Water hardness and tap water in Münster

Name: Water hardness and tap water in Münster
Creator: Trinkwassermonitor
License: https://creativecommons.org/licenses/by/4.0/

Münster, Nordrhein-Westfalen · Postcode 48143, 48145, 48149, 48151, 48155

This page is a translation of the German version; the German page is authoritative. German version · Report a translation error

Short answer: The tap water in Münster has a total hardness of 12.5 °dH, hardness range “medium” (as of 2025). All tested parameters with a legal limit (19) meet the limits set by the German Drinking Water Ordinance (TrinkwV). Source: test report by Stadtwerke Münster. WaterScore: 100 out of 100 (data coverage: 7 of 7 core parameters).

Limits of the Drinking Water OrdinancemetAll tested parameters (19), at the waterworks
Water hardness12.5 °dH, mediumNo legal limit, only a range
Data coverageCore parameters: 7 of 7Score based on complete data

Verified drinking-water values

Parameter	Value	Limit (TrinkwV)	Sampling date	Source	Status
Nitrate	5.33 mg/L 11 % of the limit	50 mg/L	2025	Stadtwerke Münster	verified
Nitrite	< 0.02 mg/L	0.5 mg/L	2025	Stadtwerke Münster	verified
PFAS (sum)	0.022 µg/L 22 % of the limit	0.1 µg/L in force since 12 January 2026 from 12 January 2028: additionally PFAS-4 0.02 µg/L	2025	Stadtwerke Münster	verified
Lead	< 0.002 mg/L	0.01 mg/L from 12 January 2028: 0.005 mg/L	2025	Stadtwerke Münster	verified
Arsenic	< 0.001 mg/L	0.01 mg/L new plants from 2028, all from 2036: 0.004 mg/L	2025	Stadtwerke Münster	verified
Uranium	0.001 mg/L 10 % of the limit	0.01 mg/L	2025	Stadtwerke Münster	verified
Mercury	< 0.0001 mg/L	0.001 mg/L	2025	Stadtwerke Münster	verified
Copper	< 0.002 mg/L	2 mg/L	2025	Stadtwerke Münster	verified
Cadmium	< 0.0002 mg/L	0.003 mg/L	2025	Stadtwerke Münster	verified
Chromium	< 0.0005 mg/L	0.025 mg/L from 12 January 2030: 0.005 mg/L	2025	Stadtwerke Münster	verified
Nickel	< 0.002 mg/L	0.02 mg/L	2025	Stadtwerke Münster	verified
Chloride	42.9 mg/L 17 % of the limit	250 mg/L	2025	Stadtwerke Münster	verified
Sulphate	51.5 mg/L 21 % of the limit	250 mg/L	2025	Stadtwerke Münster	verified
Sodium	26.5 mg/L 13 % of the limit	200 mg/L	2025	Stadtwerke Münster	verified
Calcium	79.2 mg/L	–	2025	Stadtwerke Münster	verified
Magnesium	6 mg/L	–	2025	Stadtwerke Münster	verified
pH	7.4	6.5–9.5	2025	Stadtwerke Münster	verified
Total hardness	12.5 °dH (medium)	no legal limit	2025	Stadtwerke Münster	verified
Electrical conductivity	575 µS/cm	–	2025	Stadtwerke Münster	verified
Fluoride	0.15 mg/L 10 % of the limit	1.5 mg/L	2025	Stadtwerke Münster	verified
Iron	< 0.04 mg/L	0.2 mg/L	2025	Stadtwerke Münster	verified
Manganese	< 0.03 mg/L	0.05 mg/L	2025	Stadtwerke Münster	verified
Ammonium	< 0.1 mg/L	0.5 mg/L	2025	Stadtwerke Münster	verified
Coliform bacteria	0 KBE/100ml	0 per 100 ml	2025	Stadtwerke Münster	verified

Note from the test report (in the German original): Stadtwerke Münster · Jahresmittelwerte 2025 (Dokument vom 13.08.2026) für das Wasserwerk Hohe Ward. Münster wird zusätzlich aus den Wasserwerken Vennheide (16,9 °dH, hart) und Hornheide (15,1 °dH, hart) sowie über einen Bezug von Gelsenwasser (11,0 °dH, mittel) versorgt. Im Wasserwerk Hornheide geht laut Stadtwerken im August 2026 eine Aufbereitungsanlage in Betrieb, die die Härte dort künftig in den mittleren Bereich senkt. Die Summe PFAS-20 lag in allen vier Wässern zwischen 0,000018 und 0,000022 mg/l (18 bis 22 ng/l), die Summe PFAS-4 im Wasserwerk Hohe Ward bei 0,000008 mg/l – jeweils als Jahresmittel aus drei bis vier Proben.

Is a value wrong or out of date? Report an error – we check every report against the original source.

Water at your own tap: The values describe the water the supplier delivers – not automatically the water at your tap. The water supplier is responsible up to the service connection (Hausanschluss); the building owner is responsible for the pipes beyond it. Lead can dissolve from lead pipes, leaded solder joints or old brass fittings, especially when water has stood in the pipes for a long time (stagnant water); this mainly affects buildings constructed before about 1973. If water has stood in the pipes for several hours, let it run until it comes out cool. If you suspect lead pipes, a lead analysis of the stagnant water by an accredited laboratory will help.

Background on household plumbing, not a measurement: in Münster, 43 % of buildings with living space were built before 1970, and a further 15 % 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 Münster

Nitrate 5.33 mg/L – about 11 % of the limit of 50 mg/L and in the unremarkable range. Boiling does not reduce nitrate.
PFAS (sum of PFAS-20) 22 ng/L – about 22 % 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 1 µg/L – unremarkable against a limit of 10 µg/L. In some regions uranium occurs naturally from the rock (geogenic).
pH 7.4 – 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 Münster in everyday life

At 12.5 °dH, Münster 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 Münster 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 Münster 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)

Values at the waterworks next to the maximum levels for bottled water “suitable for infant food”
Substance	Maximum level	Value in Münster
Sodium	20 mg/l	26.5 mg/l – above
Nitrate	10 mg/l	5.33 mg/l – not above
Nitrite	0.02 mg/l	below the detection limit (0.02 mg/l) – not above
Sulphate	240 mg/l	51.5 mg/l – not above
Fluoride	0.7 mg/l	0.15 mg/l – not above
Manganese	0.05 mg/l	below the detection limit (0.03 mg/l) – not above
Arsenic	0.005 mg/l	below the detection limit (0.001 mg/l) – not above
Uranium	0.002 mg/l	0.001 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 Münster

Can you drink the tap water in Münster?

According to the verified values, yes: All tested parameters with a legal limit (19) 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 Münster?

The total hardness is 12.5 °dH – hardness range “medium”. Dose detergent for the hardness range “medium”.

Is there PFAS in the tap water in Münster?

Yes, in measurable amounts: according to the published analysis by Stadtwerke Münster (as of 2025), the sum of PFAS-20 is 0.022 (middle of the range given by the supplier) µg/l – that is 22 % of the limit of 0.1 µg/l, which has applied since 12 January 2026.

Do I need to filter my tap water in Münster?

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

Qualität des Trinkwassers – Jahresmittelwerte der Trinkwasseranalysen 2025, Wasserwerk Hohe Ward (Stadtwerke Münster) · SHA-256 of the evaluated file: f97c1327edcc5c25…, checked on 3 October 2026

Suggested citation: Trinkwassermonitor (2025): Tap water in Münster. Values according to the water supplier’s test report, sampling date 2025; at the waterworks, not household plumbing. https://trinkwassermonitor.ink/en/tap-water/muenster/

JSON: /api/v1/evidence?city=muenster

Data as of: 2025 · verified: 24 of 24 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 Münster. Retrieved from https://trinkwassermonitor.ink/en/tap-water/muenster/.”