Water hardness in Oñati
13.2 °fH hard
Tap water in Oñati is hard: 13.2 °fH (132 mg/L · 7.7 gpg · 7.4 °dH).
Source: SINAC, Ministerio de Sanidad — Información de un abastecimiento, municipio 20059 (2025-04) · data checked 2026-10-19
Range across supply zones: 36–153 mg/L.
SINAC, the Ministry of Health's drinking-water register, reports 132 mg/L CaCO₃ for Oñati, hard, with a wide range from 36 to 153 mg/L. Nearby Gipuzkoa towns run from 59.5 to 191.5 mg/L, so the source in use matters. Scale builds up on kettles and taps at the harder end.
Fuentes españolas usan °fH (grados hidrotimétricos franceses) o mg/L CaCO₃.
Water data
| Total hardness | 13.2 °fH |
|---|
How Oñati compares
- Tap water in Oñati is 34 % softer than the median of the 4988 cities we track in Spain (20.1 °fH).
- By hardness it ranks 3235 of 4988 in Spain (1 = hardest); 35 % of these cities have softer water.
- In Guipúzcoa it is number 60 of 86 cities; the regional median is 15.3 °fH.
- Nearest city with clearly softer water: Legazpi, 5 km away (6.7 °fH).
- Nearest city with clearly harder water: Zegama, 11 km away (19.1 °fH).
Ranking of the hardest and softest water in Spain →
What it means at home
- Fast scale on taps, shower screens and kettle; white spots on glassware.
- Water heater: efficiency loss and element failures within years if unprotected.
- Dry skin and dull hair after showering are common.
- Softener recommended; jug or reverse osmosis for drinking.
How much salt will you use for softening?
Recommended, especially with a heater or boiler: scale cuts efficiency and shortens its life.
Descale a coffee machine or kettle about every 2 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Oñati
| Brand | Setting for this water |
|---|---|
| Bosch | H01 |
| Miele | 7 °dH |
| AEG / Electrolux | 2 |
| Beko | 2nd |
| Hoover | S1 |
| LG | H2 |
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 Oñati water hard or soft?
It is hard: 132 mg/L as CaCO₃ (7.7 gpg, 7.4 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Oñati 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 Oñati water?
7.7 gpg, equal to 7.4 °dH, 13.2 °fH or 132 mg/L calcium carbonate.
What dishwasher salt setting should I use in Oñati?
For 132 mg/L (7.4 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Oñati?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: SINAC, Ministerio de Sanidad — Información de un abastecimiento, municipio 20059 (2025-04). Method: own measurement. SINAC, Ministerio de Sanidad — Información de un abastecimiento, municipio 20059 · Outdated figure? Tell us