Water hardness in Trnava
4 mmol/L very hard
Tap water in Trnava is very hard: 4 mmol/L (400 mg/L · 23.4 gpg · 22.4 °dH).
Source: Trnavská vodárenská spoločnosť (TAVOS) (2022) · data checked 2026-10-20
This figure is over 3 years old; hardness may have changed.
TAVOS supplies this town; water supply in the western Slovak lowlands relies largely on groundwater. The reported hardness is 400.4 mg/L CaCO₃. This figure dates from 2022 and may have changed. Scale forms fast on heaters and fittings; a water softener is a common remedy.
Slovak suppliers report "Vápnik a horčík" in mmol/L; the recommended range is 1.1–5 mmol/L.
Water data
| Total hardness | 4 mmol/L |
|---|---|
| Calcium (mg/L) | 89.9 |
| Magnesium (mg/L) | 41.9 |
| Utility | Trnavská vodárenská spoločnosť (TAVOS) |
How Trnava compares
- Tap water in Trnava is 111 % harder than the median of the 1113 cities we track in Slovakia (1.9 mmol/L).
- By hardness it ranks 72 of 1113 in Slovakia (1 = hardest); 94 % of these cities have softer water.
- In Trnava Region it is number 35 of 98 cities; the regional median is 3.7 mmol/L.
- Nearest city with clearly softer water: Boleráz, 12 km away (3.2 mmol/L).
- Nearest city with clearly harder water: Pečeňady, 15 km away (5.7 mmol/L).
Ranking of the hardest and softest water in Slovakia →
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 Trnava
| Brand | Setting for this water |
|---|---|
| Bosch | H06 |
| Miele | 22 °dH |
| AEG / Electrolux | 5 |
| Beko | 6th |
| Hoover | S3 |
| LG | H4 |
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 Trnava water hard or soft?
It is very hard: 400 mg/L as CaCO₃ (23.4 gpg, 22.4 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Trnava safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. Slovak suppliers report "Vápnik a horčík" in mmol/L; the recommended range is 1.1–5 mmol/L.
How many grains per gallon is Trnava water?
23.4 gpg, equal to 22.4 °dH, 40 °fH or 400 mg/L calcium carbonate.
What dishwasher salt setting should I use in Trnava?
For 400 mg/L (22.4 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Trnava?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Trnavská vodárenská spoločnosť (TAVOS) (2022). Method: figure published by the water supplier. Trnavská vodárenská spoločnosť (TAVOS) · Outdated figure? Tell us