Hardness, nitrates, pH, sanitary compliance: the real tap water quality in Saint-Louis (very soft water), with official Hub'Eau data updated monthly.
✓ Compliant with sanitary standardsTap water in Saint-Louis has a hardness of 7.6°f — a very low level placing the city in the "very soft" category. Ideal for appliances: scale barely forms and detergent use can be reduced. However, low mineral content makes the water slightly aggressive on metals; activated charcoal filters are generally more appropriate here than water softeners. Official sanitary tests declare it compliant with current standards across all monitored parameters.
Results from the latest official sanitary samples (Hub’Eau, French Ministry of Health). Click a card to understand what each parameter measures.
Sanitary compliance summarises adherence to French regulatory limits across all analysed parameters (bacteriology, chemistry, radioactivity). Compliant water can be consumed directly from the tap without additional treatment.
The TH (titre hydrotimétrique) measures calcium and magnesium concentration, expressed in French degrees (°f). The higher it is, the harder the water and the faster limescale deposits on surfaces and in appliances.
Nitrates come mainly from agriculture and waste water. The French regulatory limit is 50 mg/L; below 25 mg/L, the level is considered low.
PFAS are persistent chemical compounds, sometimes called "forever chemicals", used in industry. The vigilance threshold used here is 0.1 µg/L, consistent with current health recommendations.
pH measures water acidity. Regulations require a value between 6.5 and 9: outside this range, water may encourage pipe corrosion or affect taste.
Free chlorine is added to disinfect water and prevent bacterial growth in the distribution network. High levels can produce a perceptible taste or odour, without health risk at authorised levels.
Turbidity measures water clarity, in NTU (nephelometric turbidity units). A low value indicates clear water with few suspended particles.
Conductivity reflects overall water mineralisation, in µS/cm. It has no strict sanitary threshold but indicates the dissolved mineral salt content.
Maintenance budget: ~£21/year
For 2 persons, water at 7.6°f deposits around 0.4 kg of limescale per year in your appliances. Estimated cost in descalers, salt and filters.
Calcium: ~12 mg per litre
Your water provides 12 mg of calcium/L, which is 1% of the recommended daily intake.
Filtration not required
Your soft water does not require filtration. A jug filter remains useful for taste.
Drinking water in Saint-Louis, in the La Réunion department is managed by runeo, which handles production, treatment and distribution of tap water in the municipality. The last available official sanitary analysis for Saint-Louis dates from 19 June 2026.
Compare the water quality in Saint-Louis with any other city available on the site.
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How does Saint-Louis compare to the 24 cities in the La Réunion department and the 4806 largest cities in France in our database, on key water quality indicators.
Comparison based on 24 cities in La Réunion department and the 4806 largest cities in France in our database.
Top 10 cities in the La Réunion department ranked by tap water quality in our database.
Saint-Louis ranks 8th out of 24 cities in the department in our database.
Tap water in Saint-Louis has a quality index of 6.9/10 (good quality) in our database, calculated on nitrates, PFAS, pH, free chlorine and turbidity. This is a comparative reading of Hub'Eau data, not an official rating.
Tap water hardness in Saint-Louis is 7.6°f (French degrees), making it very soft water. The average is 6°f in the La Réunion department and 22.1°f across our entire database.
Very little. At 7.6°f, water in Saint-Louis is very soft: limescale deposits remain minimal on taps, shower walls and heating appliances.
No. With very soft water (7.6°f), a softener would bring nothing: limescale isn't the issue in Saint-Louis.
Yes. In the last available official sanitary analysis (19 June 2026), water distributed in Saint-Louis was declared compliant, meaning it can be drunk directly from the tap. Official conclusion: "Eau d'alimentation conforme aux exigences de qualité en vigueur pour l'ensemble des paramètres mesurés." This is a point-in-time sample, not real-time monitoring.
The pH measured in Saint-Louis is 7.9. Regulations require a value between 6.5 and 9: the water is within this range.
Compare tap water quality in other cities of the La Réunion department, ranked by quality index.
Methodology: the quality index compares each city against the 4806 other cities in our database on 5 parameters (nitrates, PFAS, pH, free chlorine, turbidity) and averages its relative position on each. This is not an official rating, only a simplified comparative reading of Hub’Eau data.