Water hardness in Oulu
3.9 °dH moderately hard
Tap water in Oulu is moderately hard: 3.9 °dH (69 mg/L · 4 gpg · 6.9 °fH).
Source: City of Oulu / Oulun Vesi, Kanta-Oulun verkostoveden viranomaistarkkailun tulokset, Elokuu 2026 (2026-08) · data checked 2026-10-21
Range across supply zones: 63–80 mg/L.
Oulun Vesi publishes monitoring results for the Kanta-Oulu network. The August 2026 sheet prints an average of 0.69 mmol/L, with a minimum of 0.63 and a maximum of 0.80. That is a soft supply. Smaller networks around Oulu are run separately and are not covered by this figure.
Finnish waterworks report hardness in °dH; most supplies are soft.
Water data
| Total hardness | 3.9 °dH |
|---|---|
| Utility | Oulun Vesi (City of Oulu, Kanta-Oulu network) |
How Oulu compares
- Tap water in Oulu is 12 % harder than the median of the 76 cities we track in Finland (3.5 °dH).
- By hardness it ranks 31 of 76 in Finland (1 = hardest); 60 % of these cities have softer water.
- Nearest city with clearly softer water: Haukipudas, 19 km away (2.7 °dH).
- Nearest city with clearly harder water: Kemi, 91 km away (7.5 °dH).
Ranking of the hardest and softest water in Finland →
What it means at home
- Visible kettle scale every few weeks; vinegar or citric acid is enough.
- Water heater and washing machine: some long-term scale; a scale inhibitor slows it.
- Dishwasher: medium salt setting.
- Softener optional; pays off mainly with a gas boiler or tankless heater.
How much salt will you use for softening?
Optional. A scale inhibitor or a small softener protects the heater; soap savings are modest.
Descale a coffee machine or kettle about every 3 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Oulu
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 4 °dH |
| AEG / Electrolux | 2 |
| Beko | 1st |
| Hoover | S1 |
| LG | H1 |
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 Oulu water hard or soft?
It is moderately hard: 69 mg/L as CaCO₃ (4 gpg, 3.9 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Oulu 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 Oulu water?
4 gpg, equal to 3.9 °dH, 6.9 °fH or 69 mg/L calcium carbonate.
What dishwasher salt setting should I use in Oulu?
For 69 mg/L (3.9 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Oulu?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: City of Oulu / Oulun Vesi, Kanta-Oulun verkostoveden viranomaistarkkailun tulokset, Elokuu 2026 (2026-08). Method: figure published by the water supplier. City of Oulu / Oulun Vesi, Kanta-Oulun verkostoveden viranomaistarkkailun tulokset, Elokuu 2026 · Outdated figure? Tell us