Water hardness in Oviedo
18.1 °fH very hard
Tap water in Oviedo is very hard: 18.1 °fH (182 mg/L · 10.6 gpg · 10.2 °dH).
Source: SINAC, Ministerio de Sanidad — Información de un abastecimiento, municipio 33044 (2026-06) · data checked 2026-10-19
Range across supply zones: 89–331 mg/L.
The water comes from rivers and reservoirs on the Cantabrian slope, over limestone or siliceous rock depending on the valley. Official analyses put the water at 181.5 mg/L CaCO₃, very hard, with values between 89 and 331 mg/L depending on network, source and season. Limestone and sedimentary rock dissolve plenty of calcium and magnesium, hence the high hardness. Scale on taps and shower screens is common, and water-heater elements foul sooner.
Fuentes españolas usan °fH (grados hidrotimétricos franceses) o mg/L CaCO₃.
Water data
| Total hardness | 18.1 °fH |
|---|
How Oviedo compares
- Tap water in Oviedo is 10 % softer than the median of the 4988 cities we track in Spain (20.1 °fH).
- By hardness it ranks 2684 of 4988 in Spain (1 = hardest); 46 % of these cities have softer water.
- In Asturias it is number 6 of 49 cities; the regional median is 11.5 °fH.
- Nearest city with clearly softer water: Llanera, 10 km away (13.6 °fH).
- Nearest city with clearly harder water: Gozón, 29 km away (29.8 °fH).
Ranking of the hardest and softest water in Spain →
What it means at home
- Severe scale: heater elements and washing-machine heaters fail early.
- Detergent use is very high; taps and screens coat within days.
- Dishwasher at maximum salt setting.
- An ion-exchange softener is practically essential; RO for drinking water.
How much salt will you use for softening?
Yes. At this hardness a softener pays for itself through appliance life and detergent.
Descale a coffee machine or kettle about every 1 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Oviedo
| Brand | Setting for this water |
|---|---|
| Bosch | H02 |
| Miele | 10 °dH |
| AEG / Electrolux | 2 |
| Beko | 3rd |
| Hoover | S2 |
| 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 Oviedo water hard or soft?
It is very hard: 182 mg/L as CaCO₃ (10.6 gpg, 10.2 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Oviedo 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 Oviedo water?
10.6 gpg, equal to 10.2 °dH, 18.1 °fH or 182 mg/L calcium carbonate.
What dishwasher salt setting should I use in Oviedo?
For 182 mg/L (10.2 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Oviedo?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: SINAC, Ministerio de Sanidad — Información de un abastecimiento, municipio 33044 (2026-06). Method: own measurement. SINAC, Ministerio de Sanidad — Información de un abastecimiento, municipio 33044 · Outdated figure? Tell us