Water hardness and tap water in Saarlouis
Landkreis Saarlouis, Saarland · Postcode 66740
This page is a translation of the German version; the German page is authoritative. German version · Report a translation error
- Limits of the Drinking Water OrdinancemetAll tested parameters (13), at the waterworks
- Water hardness11 °dH, mediumNo legal limit, only a range
- Data coverageCore parameters: 3 of 7Score provisional
Verified drinking-water values
Note from the test report (in the German original): Stadtwerke Saarlouis · Untersuchungsbericht des Trinkwasserlabors der energis-Netzgesellschaft zur Probenahme am 29.04.2026 am Hochbehälter Schloßberg (Wasserwerk West), im BDEW-Wasserportal veröffentlicht. Das Wasserwerk West versorgt laut Stadtwerken das Stadtgebiet außer Roden und Fraulautern östlich der Bahnlinie und Steinrausch, die Wasser aus dem Wasserwerk Ost erhalten; das Gewerbegebiet Lisdorfer Berg beliefert energis. Der Bericht umfasst die Parameter der Gruppe B ohne Bakterien, PFAS und die Stoffe, die sich erst im Leitungsnetz ändern können. Er vermerkt den nicht relevanten Pflanzenschutzmittel-Metaboliten DMS über 0,1 µg/l; als gesundheitlicher Orientierungswert gilt dafür 1,0 µg/l.
Background on household plumbing, not a measurement: in Saarlouis, 59 % of buildings with living space were built before 1970, and a further 17 % 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 Saarlouis
- Nitrate 34.5 mg/L – about 69 % of the limit of 50 mg/L and comparatively high for a city waterworks; the cause is usually nitrate from agriculture entering the raw water. Boiling does not reduce nitrate.
- Uranium – not detectable at the waterworks (limit 10 µg/L).
- pH 7.88 – 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 Saarlouis in everyday life
At 11 °dH, Saarlouis is in the hardness range “medium” (soft: below 8.4 °dH, medium: 8.4–14 °dH, hard: above 14 °dH).
- Dose detergent for the hardness range “medium”.
- As a rule of thumb, descale the kettle about every four to six weeks and the coffee machine as the manufacturer recommends.
- A limescale protection device is not a must at medium hardness; regular descaling is often enough.
Baby food and low sodium: tap water in Saarlouis 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 Saarlouis 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)
| Substance | Maximum level | Value in Saarlouis |
|---|---|---|
| Sodium | 20 mg/l | 6.2 mg/l – not above |
| Nitrate | 10 mg/l | 34.5 mg/l – above |
| Nitrite | 0.02 mg/l | below the detection limit (0.005 mg/l) – not above |
| Sulphate | 240 mg/l | 51.9 mg/l – not above |
| Fluoride | 0.7 mg/l | 0.09 mg/l – not above |
| Manganese | 0.05 mg/l | 0.003 mg/l – not above |
| Arsenic | 0.005 mg/l | not in the report |
| Uranium | 0.002 mg/l | below the detection limit (0.0002 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 6.2 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 Saarlouis
Can you drink the tap water in Saarlouis?
According to the verified values, yes: All tested parameters with a legal limit (13) meet the limits set by the German Drinking Water Ordinance (TrinkwV). WaterScore (provisional): 97.7 out of 100 – the test report contains only 3 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 Saarlouis?
The total hardness is 11 °dH – hardness range “medium”. Dose detergent for the hardness range “medium”.
Is there PFAS in the tap water in Saarlouis?
The published analysis by Stadtwerke Saarlouis 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 Saarlouis?
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.
Is the nitrate level in Saarlouis a concern?
The value of 34.5 mg/L is below the limit of 50 mg/L, but higher than in many other evaluated cities. The limit of the Drinking Water Ordinance also applies to preparing baby food; mineral water labelled “suitable for preparing infant food” („geeignet für die Zubereitung von Säuglingsnahrung“) may contain at most 10 mg/L nitrate. Boiling does not help against nitrate.
WaterScore
- Total (provisional)97.7 / 100
- Chemical safety88.6 / 100
- Heavy metals100 / 100
- Nutrients87.8 / 100
- General parameters100 / 100
- Data timeliness100 / 100
- Data quality100 / 100
Data coverage: 3 of 7 core parameters. Not in the test report: Lead, Copper, Arsenic and PFAS (sum). Missing parameters are neither estimated nor counted as harmless: the score is based only on the values available and is therefore provisional. 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
- Untersuchungsbericht Probe 202603697, WW West / HB Schloßberg, Probenahme 29.04.2026 (Stadtwerke Saarlouis GmbH (Analyse: energis-Netzgesellschaft mbH, Trinkwasserlabor; veröffentlicht im BDEW-Wasserportal))
Suggested citation: Trinkwassermonitor (2026): Tap water in Saarlouis. Values according to the water supplier’s test report, sampling date 29 April 2026; at the waterworks, not household plumbing. https://trinkwassermonitor.ink/en/tap-water/saarlouis/
JSON: /api/v1/evidence?city=saarlouis
Data as of: 29 April 2026 · 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 Saarlouis. Retrieved from https://trinkwassermonitor.ink/en/tap-water/saarlouis/.”