Water hardness in Ostrołęka
240 mg/L very hard
Tap water in Ostrołęka is very hard: 240 mg/L (14 gpg · 13.4 °dH · 24 °fH).
Source: OPWiK Ostrołęka – SUW Kurpiowska (2026) · data checked 2026-10-29
Range across supply zones: 220–260 mg/L.
2 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| mg/L | mg/L | ||
|---|---|---|---|
| SUW Kurpiowska | 220 | 220 | very hard |
| SUW Leśna | 260 | 260 | very hard |
OPWiK Ostrołęka reports 240 mg/L CaCO₃ for water from its SUW Kurpiowska treatment plant, within a range of 220 to 260 mg/L across two zones. That is very hard water. The consequence is steady limescale in kettles, boilers and on glass. The utility page names the plant but does not describe the groundwater or surface source, so we leave that out.
Polish suppliers report total hardness in mg/L CaCO₃; the drinking-water regulation range is 60–500 mg/L.
Water data
| Total hardness | 240 mg/L |
|---|---|
| Utility | OPWiK Ostrołęka |
How Ostrołęka compares
- Tap water in Ostrołęka is close to the median of the 91 cities we track in Poland (245 mg/L).
- By hardness it ranks 50 of 91 in Poland (1 = hardest); 44 % of these cities have softer water.
- In mazowieckie it is number 12 of 17 cities; the regional median is 251 mg/L.
- Nearest city with clearly harder water: Ciechanów, 68 km away (338 mg/L).
Ranking of the hardest and softest water in Poland →
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 Ostrołęka
| 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 Ostrołęka water hard or soft?
It is very hard: 240 mg/L as CaCO₃ (14 gpg, 13.4 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Ostrołęka safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. Polish suppliers report total hardness in mg/L CaCO₃; the drinking-water regulation range is 60–500 mg/L.
How many grains per gallon is Ostrołęka water?
14 gpg, equal to 13.4 °dH, 24 °fH or 240 mg/L calcium carbonate.
What dishwasher salt setting should I use in Ostrołęka?
For 240 mg/L (13.4 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Ostrołęka?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: OPWiK Ostrołęka – SUW Kurpiowska (2026). Method: figure published by the water supplier. OPWiK Ostrołęka – SUW Kurpiowska · Outdated figure? Tell us