Water hardness and tap water in Hamm

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

Hamm, Nordrhein-Westfalen · Postcode 59063, 59065, 59067, 59068, 59069, 59070 …

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 Hamm has a total hardness of 8.3 °dH, hardness range “soft” (as of 8 April 2026). All tested parameters with a legal limit (17) meet the limits set by the German Drinking Water Ordinance (TrinkwV). Source: test report by Energie- und Wasserversorgung Hamm GmbH. WaterScore: 100 out of 100 (data coverage: 7 of 7 core parameters).

Limits of the Drinking Water OrdinancemetAll tested parameters (17), at the waterworks
Water hardness8.3 °dH, softNo 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	9.8 mg/L 20 % of the limit	50 mg/L	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Nitrite	< 0.01 mg/L	0.5 mg/L	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
PFAS (sum)	0.013 µg/L 13 % of the limit	0.1 µg/L in force since 12 January 2026 from 12 January 2028: additionally PFAS-4 0.02 µg/L	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Lead	< 0.001 mg/L	0.01 mg/L from 12 January 2028: 0.005 mg/L	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Arsenic	< 0.001 mg/L	0.01 mg/L new plants from 2028, all from 2036: 0.004 mg/L	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Uranium	< 0.001 mg/L	0.01 mg/L	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Mercury	< 0.0001 mg/L	0.001 mg/L	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Copper	< 0.1 mg/L	2 mg/L	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Chloride	28.4 mg/L 11 % of the limit	250 mg/L	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Sulphate	31 mg/L 12 % of the limit	250 mg/L	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Sodium	20 mg/L 10 % of the limit	200 mg/L	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Calcium	50 mg/L	–	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Magnesium	5.4 mg/L	–	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
pH	7.79	6.5–9.5	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Total hardness	8.3 °dH (soft)	no legal limit	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Electrical conductivity	401 µS/cm	–	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Fluoride	0.07 mg/L	1.5 mg/L	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Iron	< 0.01 mg/L	0.2 mg/L	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Manganese	< 0.002 mg/L	0.05 mg/L	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Ammonium	0.01 mg/L	0.5 mg/L	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Coliform bacteria	0 KBE/100ml	0 per 100 ml	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified
Trihalomethanes (THM)	1 µg/L	50 µg/L	8 April 2026	Energie- und Wasserversorgung Hamm GmbH	verified

Note from the test report (in the German original): Jahresmittelwerte 2025 (Dokument vom 08.04.2026) für das Wasserwerk Warmen der EWV Hamm, das den zentralen/städtischen Versorgungsbereich abdeckt. Hamm wird zusätzlich aus den Wasserwerken Echthausen und Halingen (beide Wasserwerke Westfalen) versorgt, die eigene, leicht abweichende Werte ausweisen (z. B. Gesamthärte 7,2 bzw. 7,8 °dH gegenüber 8,3 °dH in Warmen; PFAS-20 rund 20 ng/l gegenüber 13 ng/l) – der Wert für eine konkrete Adresse hängt vom zuständigen Wasserwerk ab, siehe Quelle für alle drei Zonen.

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 Hamm, 56 % of buildings with living space were built before 1970, and a further 12 % 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 Hamm

Nitrate 9.8 mg/L – about 20 % 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) 13 ng/L – about 13 % 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 7.79 – 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 Hamm in everyday life

At 8.3 °dH, Hamm 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 Hamm 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 Hamm 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 Hamm
Sodium	20 mg/l	20 mg/l – not above
Nitrate	10 mg/l	9.8 mg/l – not above
Nitrite	0.02 mg/l	below the detection limit (0.01 mg/l) – not above
Sulphate	240 mg/l	31 mg/l – not above
Fluoride	0.7 mg/l	0.07 mg/l – not above
Manganese	0.05 mg/l	below the detection limit (0.002 mg/l) – not above
Arsenic	0.005 mg/l	below the detection limit (0.001 mg/l) – not above
Uranium	0.002 mg/l	below the detection limit (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 Hamm

Can you drink the tap water in Hamm?

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 Hamm?

The total hardness is 8.3 °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 Hamm?

Yes, in measurable amounts: according to the published analysis by Energie- und Wasserversorgung Hamm GmbH (as of 8 April 2026), the sum of PFAS-20 is 0.013 (middle of the range given by the supplier) µg/l – that is 13 % of the limit of 0.1 µg/l, which has applied since 12 January 2026.

Do I need to filter my tap water in Hamm?

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

Jahrestrinkwasseranalyse 2025 (Wasserwerk Warmen) (Energie- und Wasserversorgung Hamm GmbH) · SHA-256 of the evaluated file: ad1d7c2cc6cc59c6…, checked on 3 October 2026

Suggested citation: Trinkwassermonitor (2026): Tap water in Hamm. Values according to the water supplier’s test report, sampling date 8 April 2026; at the waterworks, not household plumbing. https://trinkwassermonitor.ink/en/tap-water/hamm/

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

Data as of: 8 April 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 Hamm. Retrieved from https://trinkwassermonitor.ink/en/tap-water/hamm/.”