TrinkwassermonitorTap water in Germany

Water hardness and tap water in Erkrath

Kreis Mettmann, Nordrhein-Westfalen · Postcode 40699

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

Short answer: Depending on the address, Erkrath receives water from two supply zones: Versorgungsbereich 1 at 14.7 °dH and Versorgungsbereich 2 at 17.8 °dH, both in the hardness range “hard” (as of 2025). All tested parameters with a legal limit (31) meet the limits set by the German Drinking Water Ordinance (TrinkwV). Source: test report by Stadtwerke Erkrath. WaterScore: 100 out of 100 (data coverage: 5 of 7 core parameters).
two waters depending on the district: The values above apply to the water “Versorgungsbereich 1”, according to the supplier for laut Stadtwerken Erkrath Versorgungsbereich 1: Alt-Erkrath, Hochdahl Süd und Unterfeldhaus. Other waters: “Versorgungsbereich 2”. The supplier does not publish how many addresses each water supplies.

Verified drinking-water values: water “Versorgungsbereich 1”

ParameterValueLimit (TrinkwV)Sampling dateSourceStatus
Nitrate13.13 mg/L
50 mg/L2025Stadtwerke Erkrath GmbHverified
Nitrite< 0.01 mg/L0.5 mg/L2025Stadtwerke Erkrath GmbHverified
Lead< 0.001 mg/L0.01 mg/L
2025Stadtwerke Erkrath GmbHverified
Arsenic< 0.001 mg/L0.01 mg/L
2025Stadtwerke Erkrath GmbHverified
Copper0.033 mg/L2 mg/L2025Stadtwerke Erkrath GmbHverified
Nickel< 0.001 mg/L0.02 mg/L2025Stadtwerke Erkrath GmbHverified
Chloride63.98 mg/L
250 mg/L2025Stadtwerke Erkrath GmbHverified
Sulphate54.13 mg/L
250 mg/L2025Stadtwerke Erkrath GmbHverified
Sodium37.85 mg/L
200 mg/L2025Stadtwerke Erkrath GmbHverified
Calcium83.4 mg/L–2025Stadtwerke Erkrath GmbHverified
Magnesium12.5 mg/L–2025Stadtwerke Erkrath GmbHverified
pH7.526.5–9.52025Stadtwerke Erkrath GmbHverified
Total hardness14.7 °dH (hard)no legal limit2025Stadtwerke Erkrath GmbHverified
Electrical conductivity693.31 µS/cm–2025Stadtwerke Erkrath GmbHverified
Iron0.0555 mg/L
0.2 mg/L2025Stadtwerke Erkrath GmbHverified
Manganese0.00075 mg/L0.05 mg/L2025Stadtwerke Erkrath GmbHverified
Ammonium< 0.02 mg/L0.5 mg/L2025Stadtwerke Erkrath GmbHverified

Note from the test report (in the German original): Stadtwerke Erkrath GmbH · Trinkwasseranalyse 2025, Durchschnittswerte 2025 (Stand 04/2026); es ist nur das Jahr angegeben. Diese Werte gelten laut Stadtwerken Erkrath Versorgungsbereich 1: Alt-Erkrath, Hochdahl Süd und Unterfeldhaus; Hochdahl Nord und Willbeck bilden Versorgungsbereich 2. Die Webseite der Stadtwerke nennt für Calcium 89,35 mg/l, der datierte Bericht 83,4 mg/l (passend zur Härte von 14,7 °dH); übernommen ist der Bericht. Mehrere Stoffe wurden in diesem Bereich laut Bericht nicht untersucht. 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 Erkrath, 35 % of buildings with living space were built before 1970, and a further 29 % 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 Erkrath

Water hardness in Erkrath in everyday life

At 14.7 °dH, Erkrath is in the hardness range “hard” (soft: below 8.4 °dH, medium: 8.4–14 °dH, hard: above 14 °dH).

Baby food and low sodium: tap water in Erkrath 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 Erkrath 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”
SubstanceMaximum levelValue in Erkrath
Sodium20 mg/l37.85 mg/l – above
Nitrate10 mg/l13.13 mg/l – above
Nitrite0.02 mg/lbelow the detection limit (0.01 mg/l) – not above
Sulphate240 mg/l54.13 mg/l – not above
Fluoride0.7 mg/lnot in the report
Manganese0.05 mg/l0.00075 mg/l – not above
Arsenic0.005 mg/lbelow the detection limit (0.001 mg/l) – not above
Uranium0.002 mg/lnot in the report

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 Erkrath

Can you drink the tap water in Erkrath?

According to the verified values, yes: All tested parameters with a legal limit (31) meet the limits set by the German Drinking Water Ordinance (TrinkwV). WaterScore: 100 out of 100 (data coverage: 5 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 Erkrath?

It depends on the address: Versorgungsbereich 1 14.7 °dH and Versorgungsbereich 2 17.8 °dH – both in the 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 Erkrath?

The published analysis by Stadtwerke Erkrath 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. For the other waters, the analyses give no PFAS value.

Do I need to filter my tap water in Erkrath?

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

Data coverage: 5 of 7 core parameters. Not in the test report: Uranium and PFAS (sum). 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

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

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

Data as of: 2025 · 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 Erkrath. Retrieved from https://trinkwassermonitor.ink/en/tap-water/erkrath/.”

Further information