Water hardness in Tallinn
2.35 mmol/L very hard
Tap water in Tallinn is very hard: 2.35 mmol/L (235 mg/L · 13.7 gpg · 13.2 °dH).
Source: Terviseamet, veevärkide veeproovid (avalikud andmed) 2021–2025 (2025-05) · data checked 2026-10-19
Range across supply zones: 220–250 mg/L.
About 90% of Tallinn's consumers receive treated water from Lake Ülemiste, while outlying districts use groundwater from deep Cambrian–Vendian and Ordovician–Cambrian aquifers. The lake is fed partly by canals from the Pirita and other rivers. The reported hardness is 235.2 mg/L CaCO₃, with measurements from 220.2 to 250.2 mg/L. Scale forms fast on heaters and fittings; a water softener is a common remedy.
Estonian laboratories report total hardness (üldkaredus) in mmol/L or mg-eq/L (1 mmol/L = 2 mg-eq/L = 100 mg/L CaCO₃); groundwater supplies are mostly hard.
Water data
| Total hardness | 2.35 mmol/L |
|---|
How Tallinn compares
- Tap water in Tallinn is close to the median of the 28 cities we track in Estonia (2.32 mmol/L).
- By hardness it ranks 14 of 28 in Estonia (1 = hardest); 52 % of these cities have softer water.
- In Harjumaa it is number 3 of 11 cities; the regional median is 2.02 mmol/L.
- Nearest city with clearly softer water: Laagri, 12 km away (0.87 mmol/L).
- Nearest city with clearly harder water: Peetri, 6 km away (3.4 mmol/L).
Ranking of the hardest and softest water in Estonia →
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 Tallinn
| Brand | Setting for this water |
|---|---|
| Bosch | H04 |
| Miele | 13 °dH |
| AEG / Electrolux | 3 |
| Beko | 4th |
| 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 Tallinn water hard or soft?
It is very hard: 235 mg/L as CaCO₃ (13.7 gpg, 13.2 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Tallinn safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. Estonian laboratories report total hardness (üldkaredus) in mmol/L or mg-eq/L (1 mmol/L = 2 mg-eq/L = 100 mg/L CaCO₃); groundwater supplies are mostly hard.
How many grains per gallon is Tallinn water?
13.7 gpg, equal to 13.2 °dH, 23.5 °fH or 235 mg/L calcium carbonate.
What dishwasher salt setting should I use in Tallinn?
For 235 mg/L (13.2 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Tallinn?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Terviseamet, veevärkide veeproovid (avalikud andmed) 2021–2025 (2025-05). Method: own measurement. Terviseamet, veevärkide veeproovid (avalikud andmed) 2021–2025 · Outdated figure? Tell us