Water hardness in Castrillón
19.6 °fH very hard
Tap water in Castrillón is very hard: 19.6 °fH (196 mg/L · 11.4 gpg · 11 °dH).
Source: SINAC, Ministerio de Sanidad — Información de un abastecimiento, municipio 33016 (2026-09) · data checked 2026-10-19
Range across supply zones: 112–273 mg/L.
SINAC data from the Ministry of Health for September 2026 put Castrillón at 196 mg/L CaCO₃, with readings from 112 to 273 mg/L, so it varies a lot with the supply point and the blend at the time. In Asturias water is taken from rivers and reservoirs in the Cantabrian mountains; limestone and slate alternate in the central area, so hardness differs between municipalities. This is hard water: it leaves white marks on fittings and appliances need descaling fairly often.
Fuentes españolas usan °fH (grados hidrotimétricos franceses) o mg/L CaCO₃.
Water data
| Total hardness | 19.6 °fH |
|---|
How Castrillón compares
- Tap water in Castrillón is close to the median of the 4988 cities we track in Spain (20.1 °fH).
- By hardness it ranks 2552 of 4988 in Spain (1 = hardest); 49 % of these cities have softer water.
- In Asturias it is number 3 of 49 cities; the regional median is 11.5 °fH.
- Nearest city with clearly softer water: Avilés, 5 km away (11.5 °fH).
- Nearest city with clearly harder water: Gozón, 14 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 Castrillón
| Brand | Setting for this water |
|---|---|
| Bosch | H03 |
| Miele | 11 °dH |
| AEG / Electrolux | 3 |
| 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 Castrillón water hard or soft?
It is very hard: 196 mg/L as CaCO₃ (11.4 gpg, 11 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Castrillón 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 Castrillón water?
11.4 gpg, equal to 11 °dH, 19.6 °fH or 196 mg/L calcium carbonate.
What dishwasher salt setting should I use in Castrillón?
For 196 mg/L (11 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Castrillón?
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 33016 (2026-09). Method: own measurement. SINAC, Ministerio de Sanidad — Información de un abastecimiento, municipio 33016 · Outdated figure? Tell us