Water hardness and tap water in Erftstadt

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

Rhein-Erft-Kreis, Nordrhein-Westfalen · Postcode 50374

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 Erftstadt has a total hardness of 20.89 °dH, hardness range “hard” (as of 23 October 2024). All tested parameters with a legal limit (18) meet the limits set by the German Drinking Water Ordinance (TrinkwV). Source: test report by Stadtwerke Erftstadt. WaterScore: 94.8 out of 100 (data coverage: 6 of 7 core parameters).

Limits of the Drinking Water OrdinancemetAll tested parameters (18), at the waterworks
Water hardness20.89 °dH, hardNo legal limit, only a range
Data coverageCore parameters: 6 of 7Score based on complete data

Verified drinking-water values

Parameter	Value	Limit (TrinkwV)	Sampling date	Source	Status
Nitrate	< 0.7 mg/L	50 mg/L	23 October 2024	Stadtwerke Erftstadt	verified
Nitrite	< 0.02 mg/L	0.5 mg/L	23 October 2024	Stadtwerke Erftstadt	verified
Lead	< 0.0025 mg/L	0.01 mg/L from 12 January 2028: 0.005 mg/L	23 October 2024	Stadtwerke Erftstadt	verified
Arsenic	< 0.0005 mg/L	0.01 mg/L new plants from 2028, all from 2036: 0.004 mg/L	23 October 2024	Stadtwerke Erftstadt	verified
Uranium	< 0.0001 mg/L	0.01 mg/L	23 October 2024	Stadtwerke Erftstadt	verified
Mercury	0.00002 mg/L	0.001 mg/L	23 October 2024	Stadtwerke Erftstadt	verified
Copper	< 0.0002 mg/L	2 mg/L	23 October 2024	Stadtwerke Erftstadt	verified
Cadmium	< 0.0001 mg/L	0.003 mg/L	23 October 2024	Stadtwerke Erftstadt	verified
Chromium	< 0.001 mg/L	0.025 mg/L from 12 January 2030: 0.005 mg/L	23 October 2024	Stadtwerke Erftstadt	verified
Nickel	< 0.002 mg/L	0.02 mg/L	23 October 2024	Stadtwerke Erftstadt	verified
Chloride	50.7 mg/L 20 % of the limit	250 mg/L	23 October 2024	Stadtwerke Erftstadt	verified
Sulphate	173 mg/L 69 % of the limit	250 mg/L	23 October 2024	Stadtwerke Erftstadt	verified
Sodium	15.7 mg/L	200 mg/L	23 October 2024	Stadtwerke Erftstadt	verified
Calcium	117 mg/L	–	23 October 2024	Stadtwerke Erftstadt	verified
Magnesium	19.7 mg/L	–	23 October 2024	Stadtwerke Erftstadt	verified
pH	7.5	6.5–9.5	23 October 2024	Stadtwerke Erftstadt	verified
Total hardness	20.89 °dH (hard)	no legal limit	23 October 2024	Stadtwerke Erftstadt	verified
Electrical conductivity	770 µS/cm	–	23 October 2024	Stadtwerke Erftstadt	verified
Fluoride	0.08 mg/L	1.5 mg/L	23 October 2024	Stadtwerke Erftstadt	verified
Iron	< 0.02 mg/L	0.2 mg/L	23 October 2024	Stadtwerke Erftstadt	verified
Manganese	< 0.02 mg/L	0.05 mg/L	23 October 2024	Stadtwerke Erftstadt	verified
Ammonium	< 0.1 mg/L	0.5 mg/L	23 October 2024	Stadtwerke Erftstadt	verified
Coliform bacteria	0 KBE/100ml	0 per 100 ml	23 October 2024	Stadtwerke Erftstadt	verified

Note from the test report (in the German original): Stadtwerke Erftstadt · Prüfbericht des RWE Power Hauptlabors vom 21.03.2025, Probe vom 23.10.2024 am Wasserwerk Dirmerzheim (Reinwasser). Diese Werte gelten laut Stadtwerken Erftstadt Gymnich, Dirmerzheim, Konradsheim, Kierdorf, Köttingen, Lechenich, Herrig, Ahrem, Liblar und Blessem. Bliesheim, Friesheim, Niederberg, Borr, Scheuren und Erp erhalten ihr Wasser vom Verbandswasserwerk Euskirchen; für sie gelten diese Werte nicht. Die Website der Stadtwerke nennt eine Härte von 16–19 °dH, der Prüfbericht 3,73 mmol/l (20,9 °dH, passend zu Calcium und Magnesium); übernommen ist der datierte Prüfbericht. 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 Erftstadt, 38 % of buildings with living space were built before 1970, and a further 23 % 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 Erftstadt

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 7.5 – 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 Erftstadt in everyday life

At 20.89 °dH, Erftstadt 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 Erftstadt 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 Erftstadt 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 Erftstadt
Sodium	20 mg/l	15.7 mg/l – not above
Nitrate	10 mg/l	below the detection limit (0.7 mg/l) – not above
Nitrite	0.02 mg/l	below the detection limit (0.02 mg/l) – not above
Sulphate	240 mg/l	173 mg/l – not above
Fluoride	0.7 mg/l	0.08 mg/l – not above
Manganese	0.05 mg/l	below the detection limit (0.02 mg/l) – not above
Arsenic	0.005 mg/l	below the detection limit (0.0005 mg/l) – not above
Uranium	0.002 mg/l	below the detection limit (0.0001 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 15.7 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 Erftstadt

Can you drink the tap water in Erftstadt?

According to the verified values, yes: All tested parameters with a legal limit (18) meet the limits set by the German Drinking Water Ordinance (TrinkwV). WaterScore: 94.8 out of 100 (data coverage: 6 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 Erftstadt?

The total hardness is 20.89 °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 Erftstadt?

The published analysis by Stadtwerke Erftstadt 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 Erftstadt?

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

Total94.8 / 100
Chemical safety100 / 100
Heavy metals100 / 100
Nutrients100 / 100
General parameters88.4 / 100
Data timeliness80.1 / 100
Data quality100 / 100

Data coverage: 6 of 7 core parameters. Not in the test report: 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

Trinkwasseranalyse, Prüfbericht 2024010504-001-V1 (RWE Power Hauptlabor), Wasserwerk Dirmerzheim, Probenahme 23.10.2024 (Stadtwerke Erftstadt) · SHA-256 of the evaluated file: a467b8e5f715a9d4…, checked on 19 October 2026

Suggested citation: Trinkwassermonitor (2024): Tap water in Erftstadt. Values according to the water supplier’s test report, sampling date 23 October 2024; at the waterworks, not household plumbing. https://trinkwassermonitor.ink/en/tap-water/erftstadt/

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

Data as of: 23 October 2024 · verified: 23 of 23 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 Erftstadt. Retrieved from https://trinkwassermonitor.ink/en/tap-water/erftstadt/.”