How hard is the water in Erkrath?

Stadtwerke Düsseldorf publishes a total hardness of 2,62 mmol/l for the supply zone Hochbehälter Hardt — that corresponds to 14.7 °dH. The hardness range is a classification under the German Detergents and Cleaning Products Act (soft below 8,4 °dH, medium 8,4 to 14 °dH, hard above that) and not a quality verdict — it indicates how much calcium and magnesium is dissolved in the water. Basis: Publication by the water supplier, retrieved on 13/07/2026.

How much nitrate is in the drinking water in Erkrath?

Stadtwerke Düsseldorf publishes a nitrate value of 13,1 mg/l for the supply zone Hochbehälter Hardt. The statutory parametric value is 50 mg/l; the measured value represents 26 % of the parametric value. Basis: Publication by the water supplier, retrieved on 13/07/2026.

Who supplies the drinking water in Erkrath?

Stadtwerke Düsseldorf. The values shown here come from the supply zone Hochbehälter Hardt and apply to the water the supplier delivers. What happens between the building connection and the tap — in old lead pipes, for example — is not covered by these analyses; information on that is provided by owners, the health authority or an examination by an accredited laboratory.

Drinking water in Erkrath

4 supply zones — values can differ depending on the district. Below is the zone with the most documented parameters, the others collapsed underneath. To determine the exact match, look up the postcode.

How to read the share of the parametric value

12 % Share of the parametric value. The proportion of the permitted maximum that the measured value uses — here 12 %, so just over an eighth.

< 10 % * Below the limit of quantification. The substance was not detectable. The mark shows where the detection limit lies relative to the parametric value — the actual share of the parametric value is below that.

Several samples per year: for chemical parameters the mean value is given, for microbiological ones the highest measured value. There the parametric value is zero — a single finding would disappear in the average, and it is precisely that finding which is the information. Which reference applies is stated in the last column of the table.

Hochbehälter Hardt

Stadtwerke Düsseldorf

Assigned via the water supplier — the exact supply zone boundary within the postcode is not yet linked.

Water hardness

14.7 °dH

Hardness range hart

Key values Hochbehälter Hardt
Parameter	Value	Parametric value	Share of the parametric value	Reference
Nitrate	13,1 mg/l	50 mg/l	26 %	Mean
Lead	<0,002 mg/l below limit of quantification	10 µg/l	< 20 % *	Mean
Escherichia coli (E. coli)	0 KBE/100 ml	0/100 ml	—	Mean
Sulphate	58,2 mg/l	250 mg/l	23 %	Mean
Sodium	28,5 mg/l	200 mg/l	14 %	Mean

* Value below the limit of quantification: the actual share of the parametric value is not known; it lies somewhere below the stated upper bound. The marker shows where the limit of quantification of the measurement lies relative to the parametric value.

Show all recorded parameters (109 — most recent value per parameter)

Microbiology (2)

Microbiology – Hochbehälter Hardt
Parameter	Value	Parametric value	Share of the parametric value	Reference
Escherichia coli (E. coli)	0 KBE/100 ml	0/100 ml	—	Mean
Intestinal enterococci	0 KBE/100 ml	0/100 ml	—	Mean

Chemical parameters (53)

Chemical parameters – Hochbehälter Hardt
Parameter	Value	Parametric value	Share of the parametric value	Reference
1,2-dichloroethane	<0,2 µg/l below limit of quantification	3 µg/l	< 7 % *	Mean
2,4-D	<0,01 µg/l below limit of quantification	—	—	Mean
Antimony	<0,0008 mg/l below limit of quantification	5 µg/l	< 16 % *	Mean
Arsenic	<0,0009 mg/l below limit of quantification	10 µg/l	< 9 % *	Mean
Atrazine	<0,01 µg/l below limit of quantification	—	—	Mean
Bentazone	<0,01 µg/l below limit of quantification	—	—	Mean
Benzene	<0,2 µg/l below limit of quantification	1 µg/l	< 20 % *	Mean
Benzo(a)pyrene	<0,002 µg/l below limit of quantification	10 ng/l	< 20 % *	Mean
Benzo(b)fluoranthene	<0,005 µg/l below limit of quantification	—	—	Mean
Benzo(ghi)perylene	<0,005 µg/l below limit of quantification	—	—	Mean
Benzo(k)fluoranthene	<0,005 µg/l below limit of quantification	—	—	Mean
Bisphenol A	<0,05 µg/l below limit of quantification	2.5 µg/l	< 2 % *	Mean
Boron	<0,060 mg/l below limit of quantification	1 mg/l	< 6 % *	Mean
Bromacil	<0,01 µg/l below limit of quantification	—	—	Mean
Bromate	0,001 mg/l	10 µg/l	10 %	Mean
Bromodichloromethane	<0,2 µg/l below limit of quantification	—	—	Mean
Bromoxynil	<0,02 µg/l below limit of quantification	—	—	Mean
Cadmium	<0,0004 mg/l below limit of quantification	3 µg/l	< 13 % *	Mean
Chloridazon	<0,01 µg/l below limit of quantification	—	—	Mean
Chlorotoluron	<0,01 µg/l below limit of quantification	—	—	Mean
Chromium	<0,001 mg/l below limit of quantification	25 µg/l	< 4 % *	Mean
Copper	<0,030 mg/l below limit of quantification	2 mg/l	< 2 % *	Mean
Dibromochloromethane	<0,2 µg/l below limit of quantification	—	—	Mean
Dichloromethane	<0,2 µg/l below limit of quantification	—	—	Mean
Dichlorprop	<0,01 µg/l below limit of quantification	—	—	Mean
Dimethenamid	<0,01 µg/l below limit of quantification	—	—	Mean
Diuron	<0,01 µg/l below limit of quantification	—	—	Mean
Fluoranthene	<0,005 µg/l below limit of quantification	—	—	Mean
Fluoride	0,14 mg/l	1.5 mg/l	9 %	Mean
Indeno(1,2,3-cd)pyrene	<0,005 µg/l below limit of quantification	—	—	Mean
Isoproturon	<0,01 µg/l below limit of quantification	—	—	Mean
Lead	<0,002 mg/l below limit of quantification	10 µg/l	< 20 % *	Mean
MCPA	<0,02 µg/l below limit of quantification	—	—	Mean
Mecoprop	<0,01 µg/l below limit of quantification	—	—	Mean
Mercury	<0,00001 mg/l below limit of quantification	1 µg/l	< 1 % *	Mean
Metazachlor	<0,01 µg/l below limit of quantification	—	—	Mean
Metribuzin	<0,01 µg/l below limit of quantification	—	—	Mean
Nickel	<0,002 mg/l below limit of quantification	20 µg/l	< 10 % *	Mean
Nitrate	13,1 mg/l	50 mg/l	26 %	Mean
Nitrite	<0,01 mg/l below limit of quantification	0.5 mg/l	< 2 % *	Mean
Pesticides — Total	<0,01 µg/l below limit of quantification	0.5 µg/l	< 2 % *	Mean
Selenium	<0,002 mg/l below limit of quantification	10 µg/l	< 20 % *	Mean
Simazine	<0,01 µg/l below limit of quantification	—	—	Mean
Tebuconazole	<0,01 µg/l below limit of quantification	—	—	Mean
Terbuthylazine	<0,01 µg/l below limit of quantification	—	—	Mean
Tetrachloroethene	<0,2 µg/l below limit of quantification	—	—	Mean
Tetrachloromethane	<0,2 µg/l below limit of quantification	—	—	Mean
Tribromomethane (bromoform)	<0,2 µg/l below limit of quantification	—	—	Mean
Trichloroethene	<0,2 µg/l below limit of quantification	—	—	Mean
Trichloromethane (chloroform)	<0,2 µg/l below limit of quantification	—	—	Mean
Trihalomethanes — Total	0 µg/l	50 µg/l	0 %	Mean
Uranium	0,0006 mg/l	10 µg/l	6 %	Mean
Vinyl chloride	<0,2 µg/l below limit of quantification	0.5 µg/l	< 40 % *	Mean

Metabolites (1)

Metabolites – Hochbehälter Hardt
Parameter	Value	Parametric value	Share of the parametric value	Reference
Desphenyl-chloridazon	<0,01 µg/l below limit of quantification	—	—	Mean

Indicator parameters (20)

Indicator parameters – Hochbehälter Hardt
Parameter	Value	Parametric value	Share of the parametric value	Reference
Aluminium	<0,030 mg/l below limit of quantification	0.2 mg/l	< 15 % *	Mean
Ammonium	<0,03 mg/l below limit of quantification	0.5 mg/l	< 6 % *	Mean
Calcite dissolution capacity	-6,10 mg/l CaCO3	5 mg/l CaCO3	—	Mean
Chloride	67,9 mg/l	250 mg/l	27 %	Mean
Clostridium perfringens (including spores)	0 KBE/100 ml	0/100 ml	—	Mean
Coliform bacteria	0 KBE/100 ml	0/100 ml	—	Mean
Colony count 22 °C	1 KBE/ml	ohne anormale Veränderung	—	Mean
Colony count 36 °C	1 KBE/ml	ohne anormale Veränderung	—	Mean
Colour	<0,1 1/m below limit of quantification	0.5 m⁻¹	—	Mean
Conductivity (25 °C)	699 µS/cm	2,790 µS/cm	—	Mean
Iron	<0,020 mg/l below limit of quantification	0.2 mg/l	< 10 % *	Mean
Manganese	<0,020 mg/l below limit of quantification	50 µg/l	< 40 % *	Mean
Odour	annehmbar und ohne anormale Veränderung	für den Verbraucher annehmbar	—	Mean
pH	7,50	6,5–9,5	—	Mean
Sodium	28,5 mg/l	200 mg/l	14 %	Mean
Sulphate	58,2 mg/l	250 mg/l	23 %	Mean
Taste	annehmbar und ohne anormale Veränderung	für den Verbraucher annehmbar	—	Mean
Temperature	14,0 °C	—	—	Mean
Total organic carbon (TOC)	0,28 mg/l	ohne anormale Veränderung	—	Mean
Turbidity	0,12 FNU	1 NTU	—	Mean

Radiology (2)

Radiology – Hochbehälter Hardt
Parameter	Value	Parametric value	Share of the parametric value	Reference
Gross alpha activity	< 0,025 Bhg/l below limit of quantification	—	—	Single value
Radon-222	< 10 Bg/l below limit of quantification	100 Bq/l	—	Single value

Further parameters (31)

Further parameters – Hochbehälter Hardt
Parameter	Value	Parametric value	Share of the parametric value	Reference
Acid capacity to pH 4.3	2,00 mmol/l	—	—	Mean
Amidotrizoic acid	0,03 µg/l	—	—	Mean
Barium	0,052 mg/l	—	—	Mean
Base capacity to pH 8.2	0,10 mmol/l	—	—	Mean
Benzotriazole	<0,02 µg/l below limit of quantification	—	—	Mean
Bezafibrate	<0,01 µg/l below limit of quantification	—	—	Mean
Bromide	0,12 mg/l	—	—	Mean
Calcium	1,62 mmol/l	—	—	Mean
Candesartan	<0,01 µg/l below limit of quantification	—	—	Mean
Carbamazepine	<0,01 µg/l below limit of quantification	—	—	Mean
Diclofenac	<0,01 µg/l below limit of quantification	—	—	Mean
EDTA	<0,5 µg/l below limit of quantification	—	—	Mean
Hardness range (WRMG)	hart	—	—	Mean
Hydrogen carbonate	228 mg/l	—	—	Mean
Iomeprol	<0,01 µg/l below limit of quantification	—	—	Mean
Iopamidol	<0,01 µg/l below limit of quantification	—	—	Mean
Iopromide	<0,01 µg/l below limit of quantification	—	—	Mean
Magnesium	0,36 mmol/l	—	—	Mean
Metformin	<0,01 µg/l below limit of quantification	—	—	Mean
Oxipurinol	<0,02 µg/l below limit of quantification	—	—	Mean
Oxygen	8,30 mg/l	—	—	Mean
Pentoxifylline	<0,01 µg/l below limit of quantification	—	—	Mean
Phosphate	<0,07 mg/l below limit of quantification	—	—	Mean
Potassium	3,30 mg/l	—	—	Mean
Sotalol	<0,01 µg/l below limit of quantification	—	—	Mean
Strontium	0,453 mg/l	—	—	Mean
Sulfamethoxazole	<0,01 µg/l below limit of quantification	—	—	Mean
Thallium	<0,002 mg/l below limit of quantification	—	—	Mean
Total hardness	2,62 mmol/l	—	—	Mean
Trimethoprim	<0,01 µg/l below limit of quantification	—	—	Mean
Zinc	<0,010 mg/l below limit of quantification	—	—	Mean

Values taken unchanged from the publications linked below — for each parameter the most recent recorded value. „—" in the parametric value column: no currently valid legal parametric value is stored in our database for this parameter; the parameter register with all parametric values is being expanded continuously.

Source: https://www.swd-ag.de/pk/strom-gas-wasser/wasser/trinkwasseranalyse/ · 01.01.2025 – 31.12.2025 · retrieved on 13/07/2026

Postcodes in this zone: 40699

Show 3 more supply zones

Hochbehälter Hardt (Düsseldorf und Mettmann)

Stadtwerke Düsseldorf

Assigned via the water supplier — the exact supply zone boundary within the postcode is not yet linked.

Water hardness

14.7 °dH

Hardness range hart

Key values Hochbehälter Hardt (Düsseldorf und Mettmann)
Parameter	Value	Parametric value	Share of the parametric value	Reference
Sum of PFAS	0,001 µg/l	—	—	Single value
Nitrate	13,1 mg/l	50 mg/l	26 %	Single value
Lead	<0,002 mg/l below limit of quantification	10 µg/l	< 20 % *	Single value
Escherichia coli (E. coli)	0 MPN/100 ml	0/100 ml	—	Single value
Sulphate	58,2 mg/l	250 mg/l	23 %	Single value
Sodium	28,5 mg/l	200 mg/l	14 %	Single value

Show all recorded parameters (64 — most recent value per parameter)

Microbiology (2)

Microbiology – Hochbehälter Hardt (Düsseldorf und Mettmann)
Parameter	Value	Parametric value	Share of the parametric value	Reference
Escherichia coli (E. coli)	0 MPN/100 ml	0/100 ml	—	Single value
Intestinal enterococci	0 KBE/100 ml	0/100 ml	—	Single value

Chemical parameters (24)

Chemical parameters – Hochbehälter Hardt (Düsseldorf und Mettmann)
Parameter	Value	Parametric value	Share of the parametric value	Reference
1,2-dichloroethane	<0,2 µg/l below limit of quantification	3 µg/l	< 7 % *	Single value
Antimony	<0,0008 mg/l below limit of quantification	5 µg/l	< 16 % *	Single value
Arsenic	<0,0009 mg/l below limit of quantification	10 µg/l	< 9 % *	Single value
Benzene	<0,2 µg/l below limit of quantification	1 µg/l	< 20 % *	Single value
Benzo(a)pyrene	<0,002 µg/l below limit of quantification	10 ng/l	< 20 % *	Single value
Bisphenol A	<0,05 µg/l below limit of quantification	2.5 µg/l	< 2 % *	Single value
Boron	<0,060 mg/l below limit of quantification	1 mg/l	< 6 % *	Single value
Bromate	0,001 mg/l	10 µg/l	10 %	Single value
Cadmium	<0,0004 mg/l below limit of quantification	3 µg/l	< 13 % *	Single value
Chromium	<0,001 mg/l below limit of quantification	25 µg/l	< 4 % *	Single value
Copper	<0,030 mg/l below limit of quantification	2 mg/l	< 2 % *	Single value
Fluoride	0,13 mg/l	1.5 mg/l	9 %	Single value
Lead	<0,002 mg/l below limit of quantification	10 µg/l	< 20 % *	Single value
Mercury	<0,00001 mg/l below limit of quantification	1 µg/l	< 1 % *	Single value
Nickel	<0,002 mg/l below limit of quantification	20 µg/l	< 10 % *	Single value
Nitrate	13,1 mg/l	50 mg/l	26 %	Single value
Nitrite	<0,01 mg/l below limit of quantification	0.5 mg/l	< 2 % *	Single value
Pesticides — Total	<0,01 µg/l below limit of quantification	0.5 µg/l	< 2 % *	Single value
Polycyclic aromatic hydrocarbons	0 µg/l	0.1 µg/l	0 %	Single value
Selenium	<0,002 mg/l below limit of quantification	10 µg/l	< 20 % *	Single value
Tetrachloroethene and Trichloroethene (sum)	<0,2 µg/l below limit of quantification	10 µg/l	< 2 % *	Single value
Trihalomethanes — Total	0 µg/l	50 µg/l	0 %	Single value
Uranium	0,0006 mg/l	10 µg/l	6 %	Single value
Vinyl chloride	<0,2 µg/l below limit of quantification	0.5 µg/l	< 40 % *	Single value

PFAS (3)

PFAS – Hochbehälter Hardt (Düsseldorf und Mettmann)
Parameter	Value	Parametric value	Share of the parametric value	Reference
Sum of 4 PFAS	0 µg/l	—	—	Single value
Sum of PFAS	0,001 µg/l	—	—	Single value
Trifluoroacetic acid (TFA)	0,50 µg/L	60 µg/l UBA guide value	0.8 %	Single value

For trifluoroacetic acid (TFA), the German Drinking Water Ordinance does not specify a parametric value. The comparison is therefore made with the guide value of 60 µg/l issued by the Umweltbundesamt, which has replaced the earlier health-related guidance value of 3 µg/l. A guide value is not a legal maximum but a health-related classification.

Indicator parameters (20)

Indicator parameters – Hochbehälter Hardt (Düsseldorf und Mettmann)
Parameter	Value	Parametric value	Share of the parametric value	Reference
Aluminium	<0,030 mg/l below limit of quantification	0.2 mg/l	< 15 % *	Single value
Ammonium	<0,03 mg/l below limit of quantification	0.5 mg/l	< 6 % *	Single value
Calcite dissolution capacity	-6,10 mg/l CaCO3	5 mg/l CaCO3	—	Single value
Chloride	67,9 mg/l	250 mg/l	27 %	Single value
Clostridium perfringens (including spores)	0 KBE/100 ml	0/100 ml	—	Single value
Coliform bacteria	0 MPN/100 ml	0/100 ml	—	Single value
Colony count 22 °C	1 KBE/ml	ohne anormale Veränderung	—	Single value
Colony count 36 °C	1 KBE/ml	ohne anormale Veränderung	—	Single value
Colour	<0,1 1/m below limit of quantification	0.5 m⁻¹	—	Single value
Conductivity (25 °C)	699 µS/cm	2,790 µS/cm	—	Single value
Iron	<0,020 mg/l below limit of quantification	0.2 mg/l	< 10 % *	Single value
Manganese	<0,020 mg/l below limit of quantification	50 µg/l	< 40 % *	Single value
Odour	erfüllt -	für den Verbraucher annehmbar	—	Single value
pH	7,50 pH-Einheiten	6,5–9,5	—	Single value
Sodium	28,5 mg/l	200 mg/l	14 %	Single value
Sulphate	58,2 mg/l	250 mg/l	23 %	Single value
Taste	erfüllt -	für den Verbraucher annehmbar	—	Single value
Temperature	14,00 °C	—	—	Single value
Total organic carbon (TOC)	0,28 mg/l	ohne anormale Veränderung	—	Single value
Turbidity	0,12 FNU	1 NTU	—	Single value

Radiology (2)

Radiology – Hochbehälter Hardt (Düsseldorf und Mettmann)
Parameter	Value	Parametric value	Share of the parametric value	Reference
Gross alpha activity	< 0,025 Bq/l below limit of quantification	—	—	Single value
Radon-222	< 10 Bq/l below limit of quantification	100 Bq/l	—	Single value

Further parameters (13)

Further parameters – Hochbehälter Hardt (Düsseldorf und Mettmann)
Parameter	Value	Parametric value	Share of the parametric value	Reference
Acid capacity to pH 4.3	2,00 mmol/l	—	—	Single value
Barium	0,052 mg/l	—	—	Single value
Base capacity to pH 8.2	0,10 mmol/l	—	—	Single value
Bromide	0,12 mg/l	—	—	Single value
Calcium	1,62 mmol/l	—	—	Single value
Hardness range (WRMG)	hart	—	—	Single value
Magnesium	0,36 mmol/l	—	—	Single value
Phosphate	<0,07 mg/l below limit of quantification	—	—	Single value
Potassium	3,30 mg/l	—	—	Single value
Strontium	0,453 mg/l	—	—	Single value
Thallium	<0,002 mg/l below limit of quantification	—	—	Single value
Total hardness	2,62 mmol/l	—	—	Single value
Zinc	<0,010 mg/l below limit of quantification	—	—	Single value

Source: https://a.storyblok.com/f/274772/x/9e9ba42c93/trinkwasseranalyse-duesseldorf-2026.pdf · 01.01.2025-31.12.2025 (Hochbehälter Hardt); Radioaktivitätsparameter: 04.06.2018-31.07.2018 · retrieved on 11/07/2026

Postcodes in this zone: 40699

Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)

Stadtwerke Erkrath

Assigned via the water supplier — the exact supply zone boundary within the postcode is not yet linked.

Water hardness

14.7 °dH

Hardness range hart

Key values Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)
Parameter	Value	Parametric value	Share of the parametric value	Reference
Nitrate	13,125 mg/l	50 mg/l	26 %	Mean · Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)
Sulphate	54,125 mg/l	250 mg/l	22 %	Mean · Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)
Sodium	37,85 mg/l	200 mg/l	19 %	Mean · Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)

Show all recorded parameters (14 — most recent value per parameter)

Chemical parameters (2)

Chemical parameters – Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)
Parameter	Value	Parametric value	Share of the parametric value	Reference
Nitrate	13,125 mg/l	50 mg/l	26 %	Mean · Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)
Nitrite	<0,001 mg/l below limit of quantification	0.5 mg/l	< 0.2 % *	Mean · Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)

Indicator parameters (7)

Indicator parameters – Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)
Parameter	Value	Parametric value	Share of the parametric value	Reference
Ammonium	<0,02 mg/l below limit of quantification	0.5 mg/l	< 4 % *	Mean · Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)
Chloride	63,975 mg/l	250 mg/l	26 %	Mean · Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)
Conductivity (25 °C)	693,31 µS/cm	2,790 µS/cm	—	Mean · Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)
pH	7,52	6,5–9,5	—	Mean · Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)
Sodium	37,85 mg/l	200 mg/l	19 %	Mean · Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)
Sulphate	54,125 mg/l	250 mg/l	22 %	Mean · Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)
Total organic carbon (TOC)	1,0 mg/l	ohne anormale Veränderung	—	Mean · Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)

Further parameters (5)

Further parameters – Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)
Parameter	Value	Parametric value	Share of the parametric value	Reference
Calcium	89,35 mg/l	—	—	Mean · Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)
Hardness range (WRMG)	hart	—	—	Single value · Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)
Magnesium	12,5 mg/l	—	—	Mean · Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)
Potassium	4,025 mg/l	—	—	Mean · Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)
Total hardness	14,7 *dH	—	—	Mean · Versorgungsbereich 1 (Alt-Erkrath/ Hochdahl Süd/ Unterfeldhaus)

Source: https://www.stadtwerke-erkrath.de/wasser/trinkwasseranalyse/ · Durchschnittswerte 2025 · retrieved on 11/07/2026

Postcodes in this zone: 40699

Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)

Stadtwerke Erkrath

Assigned via the water supplier — the exact supply zone boundary within the postcode is not yet linked.

Water hardness

17,8

Hardness range hart

Key values Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)
Parameter	Value	Parametric value	Share of the parametric value	Reference
Nitrate	9,36 mg/l	50 mg/l	19 %	Mean · Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)
Sulphate	62,267 mg/l	250 mg/l	25 %	Mean · Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)
Sodium	35,6 mg/l	200 mg/l	18 %	Mean · Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)

Show all recorded parameters (14 — most recent value per parameter)

Chemical parameters (2)

Chemical parameters – Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)
Parameter	Value	Parametric value	Share of the parametric value	Reference
Nitrate	9,36 mg/l	50 mg/l	19 %	Mean · Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)
Nitrite	<0,01 mg/l below limit of quantification	0.5 mg/l	< 2 % *	Mean · Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)

Indicator parameters (7)

Indicator parameters – Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)
Parameter	Value	Parametric value	Share of the parametric value	Reference
Ammonium	0,01 mg/l	0.5 mg/l	2 %	Mean · Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)
Chloride	68,8 mg/l	250 mg/l	28 %	Mean · Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)
Conductivity (25 °C)	834,31 µS/cm	2,790 µS/cm	—	Mean · Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)
pH	7,32	6,5–9,5	—	Mean · Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)
Sodium	35,6 mg/l	200 mg/l	18 %	Mean · Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)
Sulphate	62,267 mg/l	250 mg/l	25 %	Mean · Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)
Total organic carbon (TOC)	0,7 mg/l	ohne anormale Veränderung	—	Mean · Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)

Further parameters (5)

Further parameters – Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)
Parameter	Value	Parametric value	Share of the parametric value	Reference
Calcium	95,5 mg/l	—	—	Mean · Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)
Hardness range (WRMG)	hart	—	—	Single value · Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)
Magnesium	23,0 mg/l	—	—	Mean · Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)
Potassium	2,8425 mg/l	—	—	Mean · Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)
Total hardness	17,8	—	—	Mean · Versorgungsbereich 2 (Hochdahl Nord/ Willbeck)

Source: https://www.stadtwerke-erkrath.de/wasser/trinkwasseranalyse/ · Durchschnittswerte 2025 · retrieved on 11/07/2026

Postcodes in this zone: 40699

Frequently asked questions about drinking water in Erkrath

How hard is the water in Erkrath?: Stadtwerke Düsseldorf publishes a total hardness of 2,62 mmol/l for the supply zone Hochbehälter Hardt — that corresponds to 14.7 °dH. The hardness range is a classification under the German Detergents and Cleaning Products Act (soft below 8,4 °dH, medium 8,4 to 14 °dH, hard above that) and not a quality verdict — it indicates how much calcium and magnesium is dissolved in the water. Basis: Publication by the water supplier, retrieved on 13/07/2026.
How much nitrate is in the drinking water in Erkrath?: Stadtwerke Düsseldorf publishes a nitrate value of 13,1 mg/l for the supply zone Hochbehälter Hardt. The statutory parametric value is 50 mg/l; the measured value represents 26 % of the parametric value. Basis: Publication by the water supplier, retrieved on 13/07/2026.
Who supplies the drinking water in Erkrath?: Stadtwerke Düsseldorf. The values shown here come from the supply zone Hochbehälter Hardt and apply to the water the supplier delivers. What happens between the building connection and the tap — in old lead pipes, for example — is not covered by these analyses; information on that is provided by owners, the health authority or an examination by an accredited laboratory.

General questions — how current the data is, limit of quantification, parametric values, who is behind this site — are answered under Questions & answers.