Water hardness in Ermua
16.1 °fH hard
Tap water in Ermua is hard: 16.1 °fH (161 mg/L · 9.4 gpg · 9 °dH).
Source: SINAC, Ministerio de Sanidad — Información de un abastecimiento, municipio 48034 (2025-03) · data checked 2026-10-19
Range across supply zones: 154–161 mg/L.
The hardness recorded in SINAC for Ermua is 161 mg/L CaCO₃, with readings from 154 to 161 mg/L, based on March 2025 data. 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. Some scale shows on shower screens, kettles and taps, and a scale-reduction filter can be reasonable if you want to protect appliances.
Fuentes españolas usan °fH (grados hidrotimétricos franceses) o mg/L CaCO₃.
Water data
| Total hardness | 16.1 °fH |
|---|
How Ermua compares
- Tap water in Ermua is 20 % softer than the median of the 4988 cities we track in Spain (20.1 °fH).
- By hardness it ranks 2886 of 4988 in Spain (1 = hardest); 42 % of these cities have softer water.
- In Vizcaya it is number 15 of 93 cities; the regional median is 10.1 °fH.
- Nearest city with clearly softer water: Zaldibar, 2 km away (8.9 °fH).
- Nearest city with clearly harder water: Nabarniz, 17 km away (25 °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 Ermua
| Brand | Setting for this water |
|---|---|
| Bosch | H02 |
| Miele | 9 °dH |
| AEG / Electrolux | 2 |
| Beko | 3rd |
| 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 Ermua water hard or soft?
It is hard: 161 mg/L as CaCO₃ (9.4 gpg, 9 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Ermua 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 Ermua water?
9.4 gpg, equal to 9 °dH, 16.1 °fH or 161 mg/L calcium carbonate.
What dishwasher salt setting should I use in Ermua?
For 161 mg/L (9 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Ermua?
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 48034 (2025-03). Method: own measurement. SINAC, Ministerio de Sanidad — Información de un abastecimiento, municipio 48034 · Outdated figure? Tell us