How hard is the water in Thalwil?

Gemeinde Thalwil publishes a total hardness of 26.82 °fH for the supply zone Thalwil obere Zone und Gattikon — that corresponds to 15 °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: 2025, retrieved on 07/08/2026.

How much nitrate is in the drinking water in Thalwil?

Gemeinde Thalwil publishes a nitrate value of 5.17 mg/l for the supply zone Thalwil obere Zone und Gattikon. The statutory parametric value is 40 mg/l; the measured value represents 13 % of the parametric value. Basis: 2025, retrieved on 07/08/2026.

Who supplies the drinking water in Thalwil?

Gemeinde Thalwil. The values shown here come from the supply zone Thalwil obere Zone und Gattikon 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 Thalwil

2 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.

Thalwil obere Zone und Gattikon

Gemeinde Thalwil

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

Water hardness

15 °dH

Hardness range hard

Key values Thalwil obere Zone und Gattikon
Parameter	Value	Parametric value	Share of the parametric value	Reference
Nitrate	5.17 mg/l	40 mg/l	13 %	Mean · Thalwil obere Zone und Gattikon
Escherichia coli (E. coli)	0 KBE/100ml	0/100 ml	—	Maximum · Median 0 · Thalwil obere Zone und Gattikon
Sulphate	6.94 mg/l	—	—	Mean · Thalwil obere Zone und Gattikon
Sodium	7.99 mg/l	200 mg/l	4 %	Mean · Thalwil obere Zone und Gattikon

Show all recorded parameters (13 — most recent value per parameter)

Microbiology (3)

Microbiology – Thalwil obere Zone und Gattikon
Parameter	Value	Parametric value	Share of the parametric value	Reference
Aerobic mesophilic bacteria	4.23 KBE/ml	300 1/ml	—	Mean · Thalwil obere Zone und Gattikon
Escherichia coli (E. coli)	0 KBE/100ml	0/100 ml	—	Maximum · Median 0 · Thalwil obere Zone und Gattikon
Intestinal enterococci	0 KBE/100ml	0/100 ml	—	Maximum · Median 0 · Thalwil obere Zone und Gattikon

Chemical parameters (1)

Chemical parameters – Thalwil obere Zone und Gattikon
Parameter	Value	Parametric value	Share of the parametric value	Reference
Nitrate	5.17 mg/l	40 mg/l	13 %	Mean · Thalwil obere Zone und Gattikon

Indicator parameters (6)

Indicator parameters – Thalwil obere Zone und Gattikon
Parameter	Value	Parametric value	Share of the parametric value	Reference
Chloride	11.47 mg/l	—	—	Mean · Thalwil obere Zone und Gattikon
Conductivity (25 °C)	474.63 µS/cm	—	—	Mean · Thalwil obere Zone und Gattikon
pH	7.47	—	—	Mean · Thalwil obere Zone und Gattikon
Sodium	7.99 mg/l	200 mg/l	4 %	Mean · Thalwil obere Zone und Gattikon
Sulphate	6.94 mg/l	—	—	Mean · Thalwil obere Zone und Gattikon
Temperature	12.92 °C	—	—	Mean · Thalwil obere Zone und Gattikon

Further parameters (3)

Further parameters – Thalwil obere Zone und Gattikon
Parameter	Value	Parametric value	Share of the parametric value	Reference
Calcium	93.92 mg/l	—	—	Mean · Thalwil obere Zone und Gattikon
Magnesium	8.24 mg/l	—	—	Mean · Thalwil obere Zone und Gattikon
Total hardness	26.82 °fH	—	—	Mean · Thalwil obere Zone und Gattikon

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://trinkwasser.ch/de/versorger/890/gemeinde-thalwil/3384/thalwil-obere-zone-und-gattikon · 2025 · 2025 · retrieved on 07/08/2026

Postcodes in this zone: 8800

Show 1 more supply zone

Thalwil untere Zone

Gemeinde Thalwil

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

Water hardness

11.3 °dH

Hardness range medium

Key values Thalwil untere Zone
Parameter	Value	Parametric value	Share of the parametric value	Reference
Nitrate	5.51 mg/l	40 mg/l	14 %	Mean · Thalwil untere Zone
Escherichia coli (E. coli)	0 KBE/100ml	0/100 ml	—	Maximum · Median 0 · Thalwil untere Zone
Sulphate	12.33 mg/l	—	—	Mean · Thalwil untere Zone
Sodium	5.58 mg/l	200 mg/l	3 %	Mean · Thalwil untere Zone

Show all recorded parameters (13 — most recent value per parameter)

Microbiology (3)

Microbiology – Thalwil untere Zone
Parameter	Value	Parametric value	Share of the parametric value	Reference
Aerobic mesophilic bacteria	16.66 KBE/ml	300 1/ml	—	Mean · Thalwil untere Zone
Escherichia coli (E. coli)	0 KBE/100ml	0/100 ml	—	Maximum · Median 0 · Thalwil untere Zone
Intestinal enterococci	0 KBE/100ml	0/100 ml	—	Maximum · Median 0 · Thalwil untere Zone

Chemical parameters (1)

Chemical parameters – Thalwil untere Zone
Parameter	Value	Parametric value	Share of the parametric value	Reference
Nitrate	5.51 mg/l	40 mg/l	14 %	Mean · Thalwil untere Zone

Indicator parameters (6)

Indicator parameters – Thalwil untere Zone
Parameter	Value	Parametric value	Share of the parametric value	Reference
Chloride	7.81 mg/l	—	—	Mean · Thalwil untere Zone
Conductivity (25 °C)	360.72 µS/cm	—	—	Mean · Thalwil untere Zone
pH	7.55	—	—	Mean · Thalwil untere Zone
Sodium	5.58 mg/l	200 mg/l	3 %	Mean · Thalwil untere Zone
Sulphate	12.33 mg/l	—	—	Mean · Thalwil untere Zone
Temperature	13.05 °C	—	—	Mean · Thalwil untere Zone

Further parameters (3)

Further parameters – Thalwil untere Zone
Parameter	Value	Parametric value	Share of the parametric value	Reference
Calcium	66.98 mg/l	—	—	Mean · Thalwil untere Zone
Magnesium	8.41 mg/l	—	—	Mean · Thalwil untere Zone
Total hardness	20.17 °fH	—	—	Mean · Thalwil untere Zone

Source: https://trinkwasser.ch/de/versorger/890/gemeinde-thalwil/3382/thalwil-untere-zone · 2025 · 2025 · retrieved on 07/08/2026

Postcodes in this zone: 8800

Frequently asked questions about drinking water in Thalwil

How hard is the water in Thalwil?: Gemeinde Thalwil publishes a total hardness of 26.82 °fH for the supply zone Thalwil obere Zone und Gattikon — that corresponds to 15 °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: 2025, retrieved on 07/08/2026.
How much nitrate is in the drinking water in Thalwil?: Gemeinde Thalwil publishes a nitrate value of 5.17 mg/l for the supply zone Thalwil obere Zone und Gattikon. The statutory parametric value is 40 mg/l; the measured value represents 13 % of the parametric value. Basis: 2025, retrieved on 07/08/2026.
Who supplies the drinking water in Thalwil?: Gemeinde Thalwil. The values shown here come from the supply zone Thalwil obere Zone und Gattikon 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.