Water hardness and tap water in Warendorf

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

Kreis Warendorf, Nordrhein-Westfalen · Postcode 48231

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 Warendorf has a total hardness of 14.1 °dH, hardness range “hard” (as of 27 April 2026). All tested parameters with a legal limit (12) meet the limits set by the German Drinking Water Ordinance (TrinkwV). Source: test report by Stadtwerke Warendorf. WaterScore (provisional): 100 out of 100 – the test report contains only 2 of 7 core parameters.

Limits of the Drinking Water OrdinancemetAll tested parameters (12), at the waterworks
Water hardness14.1 °dH, hardNo legal limit, only a range
Data coverageCore parameters: 2 of 7Score provisional

Verified drinking-water values

Parameter	Value	Limit (TrinkwV)	Sampling date	Source	Status
Nitrate	6 mg/L 12 % of the limit	50 mg/L	27 April 2026	Stadtwerke Warendorf	verified
Uranium	< 0.001 mg/L	0.01 mg/L	27 April 2026	Stadtwerke Warendorf	verified
Mercury	< 0.0002 mg/L	0.001 mg/L	27 April 2026	Stadtwerke Warendorf	verified
Chromium	< 0.0005 mg/L	0.025 mg/L from 12 January 2030: 0.005 mg/L	27 April 2026	Stadtwerke Warendorf	verified
Chloride	67 mg/L 27 % of the limit	250 mg/L	27 April 2026	Stadtwerke Warendorf	verified
Sulphate	67 mg/L 27 % of the limit	250 mg/L	27 April 2026	Stadtwerke Warendorf	verified
Sodium	36.2 mg/L 18 % of the limit	200 mg/L	27 April 2026	Stadtwerke Warendorf	verified
Calcium	91.7 mg/L	–	27 April 2026	Stadtwerke Warendorf	verified
Magnesium	5.3 mg/L	–	27 April 2026	Stadtwerke Warendorf	verified
pH	7.18	6.5–9.5	27 April 2026	Stadtwerke Warendorf	verified
Total hardness	14.1 °dH (hard)	no legal limit	27 April 2026	Stadtwerke Warendorf	verified
Electrical conductivity	704 µS/cm	–	27 April 2026	Stadtwerke Warendorf	verified
Fluoride	0.11 mg/L	1.5 mg/L	27 April 2026	Stadtwerke Warendorf	verified
Iron	0.01 mg/L	0.2 mg/L	27 April 2026	Stadtwerke Warendorf	verified
Manganese	< 0.01 mg/L	0.05 mg/L	27 April 2026	Stadtwerke Warendorf	verified
Ammonium	< 0.05 mg/L	0.5 mg/L	27 April 2026	Stadtwerke Warendorf	verified
Coliform bacteria	0 KBE/100ml	0 per 100 ml	27 April 2026	Stadtwerke Warendorf	verified

Note from the test report (in the German original): Auszug (Seiten 10 bis 12 von 12) aus Prüfbericht A2608359, Probe vom 27.04.2026 am Reinwasser des Wasserwerks Warendorf. Die Stadtwerke liefern laut eigener Seite nach Warendorf, Freckenhorst, Milte, Einen und Müssingen; ob alle diese Orte aus diesem Werk versorgt werden, nennt die Seite nicht. Hoetmar führt sie nicht auf. Die Härte liegt mit 14,1 °dH knapp im Bereich hart. Der Auszug enthält weder Blei, Kupfer, Arsen noch PFAS. Die Werte gelten ab Wasserwerk.

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 Warendorf, 43 % of buildings with living space were built before 1970, and a further 16 % 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 Warendorf

Nitrate 6 mg/L – about 12 % of the limit of 50 mg/L and in the unremarkable range. Boiling does not reduce nitrate.
Uranium – not detectable at the waterworks (limit 10 µg/L).
pH 7.18 – 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 Warendorf in everyday life

At 14.1 °dH, Warendorf is in the hardness range “hard” (soft: below 8.4 °dH, medium: 8.4–14 °dH, hard: above 14 °dH).

Dose detergent for the hardness range “hard” – a larger amount is needed; a water softener for the washing machine can save detergent.
Limescale builds up quickly: descale the kettle about every two to three weeks, and taps and shower heads too.
In your own house, limescale protection or a water softener can be worthwhile at this hardness; in a rented flat, the owner decides.

Baby food and low sodium: tap water in Warendorf 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 Warendorf 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)

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.

Values at the waterworks next to the maximum levels for bottled water “suitable for infant food”
Substance	Maximum level	Value in Warendorf
Sodium	20 mg/l	36.2 mg/l – above the bottled-water threshold
Nitrate	10 mg/l	6 mg/l – not above
Nitrite	0.02 mg/l	not in the report
Sulphate	240 mg/l	67 mg/l – not above
Fluoride	0.7 mg/l	0.11 mg/l – not above
Manganese	0.05 mg/l	below the detection limit (0.01 mg/l) – not above
Arsenic	0.005 mg/l	not in the report
Uranium	0.002 mg/l	below the detection limit (0.001 mg/l) – not above

Questions about baby food are answered by your midwife, your paediatrician and the health office (Gesundheitsamt).

Frequently asked questions about tap water in Warendorf

Can you drink the tap water in Warendorf?

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): 100 out of 100 – the test report contains only 2 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 Warendorf?

The total hardness is 14.1 °dH – hardness range “hard”. Dose detergent for the hardness range “hard” – a larger amount is needed; a water softener for the washing machine can save detergent.

Is there PFAS in the tap water in Warendorf?

The published analysis by Stadtwerke Warendorf that we evaluated gives no PFAS value. This does not mean there is no PFAS in the water; there is simply no figure for it. Since 12 January 2026, a limit of 0.1 µg/l has applied to the sum of PFAS-20. The supplier can tell you whether PFAS was measured and with what result.

Do I need to filter my tap water in Warendorf?

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)100 / 100
Chemical safety100 / 100
Heavy metals100 / 100
Nutrients100 / 100
General parameters100 / 100
Data timeliness100 / 100
Data quality100 / 100

Data coverage: 2 of 7 core parameters. Not in the test report: Nitrite, Lead, Copper, Arsenic and PFAS (sum). 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 v4: how we calculate the WaterScore.

Evidence: cite and check

Prüfbericht A2608359, Probe A2608359/03, Warendorf WW Reinwasser (Pumpstation), Probenahme 27.04.2026 (Stadtwerke Warendorf) · SHA-256 of the evaluated file: 6c54439b382f3955…, checked on 1 November 2026

Suggested citation: Trinkwassermonitor (2026): Tap water in Warendorf. Values according to the water supplier’s test report, sampling date 27 April 2026; at the waterworks, not household plumbing. https://trinkwassermonitor.ink/en/tap-water/warendorf/

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

Data as of: 27 April 2026 · verified: 17 of 17 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 Warendorf. Retrieved from https://trinkwassermonitor.ink/en/tap-water/warendorf/.”