Water hardness in Castano Primo
25.3 °fH very hard
Tap water in Castano Primo is very hard: 25.3 °fH (253 mg/L · 14.8 gpg · 14.2 °dH).
Source: Gruppo CAP, analisi acquedotto (open data), 2025 Q3–2026 Q2 (2026-06) · data checked 2026-10-19
Range across supply zones: 202–273 mg/L.
Gruppo CAP, the water utility for the Milan metropolitan area, publishes open analysis data for Castano Primo. Hardness is calculated from calcium and magnesium at 252.8 mg/L CaCO₃, with samples from the third quarter of 2025 to the second quarter of 2026 ranging from 202.2 to 273.1 mg/L. That is very hard water, and kettles, showerheads and boilers will scale up quickly. The page we used does not say which wells or sources feed the town, so we do not describe them here.
Italian utilities report °f (French degrees); D.Lgs. 31/2001 recommends 15–50 °f.
Water data
| Total hardness | 25.3 °fH |
|---|
How Castano Primo compares
- Tap water in Castano Primo is 19 % harder than the median of the 629 cities we track in Italy (21.2 °fH).
- By hardness it ranks 226 of 629 in Italy (1 = hardest); 64 % of these cities have softer water.
- In Lombardia it is number 68 of 142 cities; the regional median is 24.9 °fH.
- Nearest city with clearly softer water: Canegrate, 12 km away (19.3 °fH).
- Nearest city with clearly harder water: San Vittore Olona, 13 km away (33.6 °fH).
Ranking of the hardest and softest water in Italy →
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 Castano Primo
| 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 Castano Primo water hard or soft?
It is very hard: 253 mg/L as CaCO₃ (14.8 gpg, 14.2 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Castano Primo safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. Italian utilities report °f (French degrees); D.Lgs. 31/2001 recommends 15–50 °f.
How many grains per gallon is Castano Primo water?
14.8 gpg, equal to 14.2 °dH, 25.3 °fH or 253 mg/L calcium carbonate.
What dishwasher salt setting should I use in Castano Primo?
For 253 mg/L (14.2 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Castano Primo?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Gruppo CAP, analisi acquedotto (open data), 2025 Q3–2026 Q2 (2026-06). Method: computed from supplier's calcium and magnesium. Gruppo CAP, analisi acquedotto (open data), 2025 Q3–2026 Q2 · Outdated figure? Tell us