Water hardness in Hernani
3.9 °fH soft
Tap water in Hernani is soft: 3.9 °fH (39 mg/L · 2.2 gpg · 2.2 °dH).
Source: SINAC, Ministerio de Sanidad — Información de un abastecimiento, municipio 20040 (2025-09) · data checked 2026-10-19
Range across supply zones: 19–58 mg/L.
The hardness recorded in SINAC for Hernani is 38.5 mg/L CaCO₃, with readings from 19 to 58 mg/L, based on September 2025 data, so it varies a lot with the supply point and the blend at the time. In the Basque Country water comes from reservoirs and springs on the Cantabrian side, with limestone and marl in the massifs and sandstone elsewhere; hardness runs from low to moderate. At this level scale barely builds up on taps or appliances, and a softener is rarely worth installing.
Fuentes españolas usan °fH (grados hidrotimétricos franceses) o mg/L CaCO₃.
Water data
| Total hardness | 3.9 °fH |
|---|
How Hernani compares
- Tap water in Hernani is 81 % softer than the median of the 4988 cities we track in Spain (20.1 °fH).
- By hardness it ranks 4329 of 4988 in Spain (1 = hardest); 13 % of these cities have softer water.
- In Guipúzcoa it is number 83 of 86 cities; the regional median is 15.3 °fH.
- Nearest city with clearly softer water: Oiartzun, 8 km away (1.5 °fH).
- Nearest city with clearly harder water: Astigarraga, 5 km away (4.9 °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 Hernani
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 2 °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 Hernani water hard or soft?
It is soft: 39 mg/L as CaCO₃ (2.2 gpg, 2.2 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Hernani 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 Hernani water?
2.2 gpg, equal to 2.2 °dH, 3.9 °fH or 39 mg/L calcium carbonate.
What dishwasher salt setting should I use in Hernani?
For 39 mg/L (2.2 °dH) check your manufacturer's table: level 0–1, usually no salt.
Do I need a water softener in Hernani?
No. With soft water a softener adds nothing.
Source
Source: SINAC, Ministerio de Sanidad — Información de un abastecimiento, municipio 20040 (2025-09). Method: own measurement. SINAC, Ministerio de Sanidad — Información de un abastecimiento, municipio 20040 · Outdated figure? Tell us