Water hardness in Rauma
7.1 °dH hard
Tap water in Rauma is hard: 7.1 °dH (127 mg/L · 7.4 gpg · 12.7 °fH).
Source: Rauman Vesi, Toimintakertomus 2024 (2024) · data checked 2026-10-23
Range across supply zones: 118–136 mg/L.
Finnish waterworks use lake water, often treated or recharged through glacial esker deposits, or natural groundwater. Hardness here is above what the mostly granite bedrock would suggest, so local deposits or the supplier's source are likely to play a role. The reported hardness is 126.7 mg/L CaCO₃, with measurements from 117.8 to 135.7 mg/L. Heating elements and taps scale up noticeably; a softener or scale filter can reduce the buildup.
Finnish waterworks report hardness in °dH; most supplies are soft.
Water data
| Total hardness | 7.1 °dH |
|---|---|
| Utility | Rauman Vesi |
How Rauma compares
- Tap water in Rauma is 105 % harder than the median of the 76 cities we track in Finland (3.5 °dH).
- By hardness it ranks 5 of 76 in Finland (1 = hardest); 95 % of these cities have softer water.
- Nearest city with clearly softer water: Eura, 33 km away (5.1 °dH).
Ranking of the hardest and softest water in Finland →
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 Rauma
| 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 Rauma water hard or soft?
It is hard: 127 mg/L as CaCO₃ (7.4 gpg, 7.1 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Rauma safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. Finnish waterworks report hardness in °dH; most supplies are soft.
How many grains per gallon is Rauma water?
7.4 gpg, equal to 7.1 °dH, 12.7 °fH or 127 mg/L calcium carbonate.
What dishwasher salt setting should I use in Rauma?
For 127 mg/L (7.1 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Rauma?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: Rauman Vesi, Toimintakertomus 2024 (2024). Method: computed from supplier's calcium and magnesium. Rauman Vesi, Toimintakertomus 2024 · Outdated figure? Tell us