Water hardness in Donostia / San Sebastián
5.6 °fH soft
Tap water in Donostia / San Sebastián is soft: 5.6 °fH (56 mg/L · 3.3 gpg · 3.1 °dH).
Source: SINAC, Ministerio de Sanidad — Información de un abastecimiento, municipio 20069 (2025-12) · data checked 2026-10-19
Range across supply zones: 51–62 mg/L.
The water comes from mountain reservoirs and springs in a high-rainfall area. Official analyses put the water at 56 mg/L CaCO₃, soft, with values between 51 and 62 mg/L. Appliances gather little scale; it is enough to dose detergent sensibly.
Fuentes españolas usan °fH (grados hidrotimétricos franceses) o mg/L CaCO₃.
Water data
| Total hardness | 5.6 °fH |
|---|
How Donostia / San Sebastián compares
- Tap water in Donostia / San Sebastián is 72 % softer than the median of the 4988 cities we track in Spain (20.1 °fH).
- By hardness it ranks 4109 of 4988 in Spain (1 = hardest); 18 % of these cities have softer water.
- In Guipúzcoa it is number 77 of 86 cities; the regional median is 15.3 °fH.
- Nearest city with clearly softer water: Hernani, 7 km away (3.9 °fH).
- Nearest city with clearly harder water: Andoain, 8 km away (16.3 °fH).
Ranking of the hardest and softest water in Spain →
What it means at home
- Little or no limescale in kettles, water heaters or washing machines.
- Soap lathers easily; water does not dry skin or hair.
- Dishwasher: salt setting at minimum or off.
- No softener needed; a jug filter only changes taste.
How much salt will you use for softening?
No. Water this soft does not need softening.
Descale a coffee machine or kettle about every 6 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Donostia / San Sebastián
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 3 °dH |
| AEG / Electrolux | 1 |
| Beko | 1st |
| Hoover | S0 |
| LG | H0 |
From each brand's manual for the model family named in the source; your model may differ, so check its manual. All brands and how to change the setting →
FAQ
Is Donostia / San Sebastián water hard or soft?
It is soft: 56 mg/L as CaCO₃ (3.3 gpg, 3.1 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Donostia / San Sebastián safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. Fuentes españolas usan °fH (grados hidrotimétricos franceses) o mg/L CaCO₃.
How many grains per gallon is Donostia / San Sebastián water?
3.3 gpg, equal to 3.1 °dH, 5.6 °fH or 56 mg/L calcium carbonate.
What dishwasher salt setting should I use in Donostia / San Sebastián?
For 56 mg/L (3.1 °dH) check your manufacturer's table: level 0–1, usually no salt.
Do I need a water softener in Donostia / San Sebastián?
No. With soft water a softener adds nothing.
Source
Source: SINAC, Ministerio de Sanidad — Información de un abastecimiento, municipio 20069 (2025-12). Method: own measurement. SINAC, Ministerio de Sanidad — Información de un abastecimiento, municipio 20069 · Outdated figure? Tell us