Water hardness in Onda
52 °fH very hard
Tap water in Onda is very hard: 52 °fH (520 mg/L · 30.3 gpg · 29.1 °dH).
Source: SINAC, Ministerio de Sanidad — Información de un abastecimiento, municipio 12084 (2026-06) · data checked 2026-10-21
Range across supply zones: 485–630 mg/L.
Water comes from wells on the coastal plain and from the province's river basins, over limestone terrain. Official analyses put the water at 519.5 mg/L CaCO₃, very hard, with values between 485 and 630 mg/L. Limestone and sedimentary rock dissolve plenty of calcium and magnesium, hence the high hardness. Scale deposits quickly in kettles, heaters and heating elements; many households fit a softener.
Fuentes españolas usan °fH (grados hidrotimétricos franceses) o mg/L CaCO₃.
Water data
| Total hardness | 52 °fH |
|---|
How Onda compares
- Tap water in Onda is 158 % harder than the median of the 4988 cities we track in Spain (20.1 °fH).
- By hardness it ranks 211 of 4988 in Spain (1 = hardest); 96 % of these cities have softer water.
- In Castellón/Castelló it is number 19 of 134 cities; the regional median is 33.6 °fH.
- Nearest city with clearly softer water: Betxí, 8 km away (39.7 °fH).
- Nearest city with clearly harder water: Alcora, l', 8 km away (72.6 °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 Onda
| Brand | Setting for this water |
|---|---|
| Bosch | H06 |
| Miele | 29 °dH |
| AEG / Electrolux | 7 |
| Beko | 6th |
| Hoover | S4 |
| LG | H4 |
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 Onda water hard or soft?
It is very hard: 520 mg/L as CaCO₃ (30.3 gpg, 29.1 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Onda 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 Onda water?
30.3 gpg, equal to 29.1 °dH, 52 °fH or 520 mg/L calcium carbonate.
What dishwasher salt setting should I use in Onda?
For 520 mg/L (29.1 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Onda?
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 12084 (2026-06). Method: own measurement. SINAC, Ministerio de Sanidad — Información de un abastecimiento, municipio 12084 · Outdated figure? Tell us