Water hardness in Viljandi
2.57 mmol/L very hard
Tap water in Viljandi is very hard: 2.57 mmol/L (258 mg/L · 15.1 gpg · 14.4 °dH).
Source: Terviseamet, veevärkide veeproovid (avalikud andmed) 2021–2025 (2025-11) · data checked 2026-10-19
Range across supply zones: 247–260 mg/L.
Estonia relies largely on groundwater from limestone and dolomite aquifers in the north and sandstone further south, which gives hard water. The reported hardness is 257.7 mg/L CaCO₃, with measurements from 246.7 to 260.2 mg/L. Appliances scale up quickly at this level, and a softener is worth considering.
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 | 2.57 mmol/L |
|---|
How Viljandi compares
- Tap water in Viljandi is 11 % harder than the median of the 28 cities we track in Estonia (2.32 mmol/L).
- By hardness it ranks 10 of 28 in Estonia (1 = hardest); 67 % of these cities have softer water.
- Nearest city with clearly softer water: Rapla, 85 km away (1.9 mmol/L).
- Nearest city with clearly harder water: Paide, 58 km away (3.72 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 Viljandi
| Brand | Setting for this water |
|---|---|
| Bosch | H04 |
| Miele | 14 °dH |
| AEG / Electrolux | 3 |
| Beko | 4th |
| Hoover | S2 |
| LG | H3 |
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 Viljandi water hard or soft?
It is very hard: 258 mg/L as CaCO₃ (15.1 gpg, 14.4 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Viljandi 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 Viljandi water?
15.1 gpg, equal to 14.4 °dH, 25.8 °fH or 258 mg/L calcium carbonate.
What dishwasher salt setting should I use in Viljandi?
For 258 mg/L (14.4 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Viljandi?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Terviseamet, veevärkide veeproovid (avalikud andmed) 2021–2025 (2025-11). Method: own measurement. Terviseamet, veevärkide veeproovid (avalikud andmed) 2021–2025 · Outdated figure? Tell us