Water hardness in Prague
1.56 mmol/L hard
Tap water in Prague is hard: 1.56 mmol/L (156 mg/L · 9.1 gpg · 8.7 °dH).
Source: PVK, Pražské vodovody a kanalizace, a.s. - Kvalita pitné vody, half-year averages Jan-Jun 2026 (2026-06) · data checked 2026-10-21
Range across supply zones: 108–221 mg/L.
PVK supplies Prague from five source mixes built on the Želivka and Káraný waterworks, with Podolí blended in some zones. Its January to June 2026 averages run from 1.08 mmol/L (Želivka alone) to 2.21 mmol/L (Káraný alone), about 108 to 221 mg/L CaCO₃. The city figure of 1.56 mmol/L, about 156 mg/L, is the unweighted median of the five zones, not a population-weighted average. The 2 to 3.5 mmol/L printed on the PVK sheets is a recommended range, not a measurement, so check which mix reaches your street.
Czech suppliers report "Vápník a hořčík" in mmol/L; the recommended range is 2–3.5 mmol/L.
Water data
| Total hardness | 1.56 mmol/L |
|---|---|
| period | 2026-01 to 2026-06 averages |
| zone_values_mmol_l | [object Object] |
| zone_pdfs | https://www.pvk.cz/res/archive/1277/266469.pdf,https://www.pvk.cz/res/archive/1190/266470.pdf,https://www.pvk.cz/res/archive/1106/266467.pdf,https://www.pvk.cz/res/archive/1137/266468.pdf,https://www.pvk.cz/res/archive/1234/266471.pdf |
| row | vapnik a horcik mmol/l (Ca+Mg, printed as average) |
| Utility | Pražské vodovody a kanalizace, a.s. (PVK) |
How Prague compares
- Tap water in Prague is 30 % harder than the median of the 1516 cities we track in Czechia (1.2 mmol/L).
- By hardness it ranks 463 of 1516 in Czechia (1 = hardest); 69 % of these cities have softer water.
- Nearest city with clearly softer water: Roztoky, 8 km away (1.12 mmol/L).
- Nearest city with clearly harder water: Kladno, 24 km away (3.1 mmol/L).
Ranking of the hardest and softest water in Czechia →
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 Prague
| Brand | Setting for this water |
|---|---|
| Bosch | H02 |
| Miele | 9 °dH |
| AEG / Electrolux | 2 |
| Beko | 3rd |
| 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 Prague water hard or soft?
It is hard: 156 mg/L as CaCO₃ (9.1 gpg, 8.7 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Prague safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. Czech suppliers report "Vápník a hořčík" in mmol/L; the recommended range is 2–3.5 mmol/L.
How many grains per gallon is Prague water?
9.1 gpg, equal to 8.7 °dH, 15.6 °fH or 156 mg/L calcium carbonate.
What dishwasher salt setting should I use in Prague?
For 156 mg/L (8.7 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Prague?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: PVK, Pražské vodovody a kanalizace, a.s. - Kvalita pitné vody, half-year averages Jan-Jun 2026 (2026-06). Method: computed from supplier's calcium and magnesium. PVK, Pražské vodovody a kanalizace, a.s. - Kvalita pitné vody, half-year averages Jan-Jun 2026 · Outdated figure? Tell us