Water hardness in Guidonia
31.6 °fH very hard
Tap water in Guidonia is very hard: 31.6 °fH (316 mg/L · 18.5 gpg · 17.7 °dH).
Source: Acea Ato 2, qualità dell'acqua, scheda di zona (valori mediani) (2026-07) · data checked 2026-10-29
The supply to Guidonia comes through Acea Ato 2, which relies mainly on spring water from the Apennines plus local sources; we have not matched Guidonia to a single intake. The reported figure is 316.0 mg/L CaCO₃, which counts as very hard water. Kettles, steam irons and dishwashers collect scale fast at this level, and a softener is a common answer.
Italian utilities report °f (French degrees); D.Lgs. 31/2001 recommends 15–50 °f.
Water data
| Total hardness | 31.6 °fH |
|---|---|
| calcio_mg_l | 89.45 |
| magnesio_mg_l | 22.35 |
| Utility | Acea Ato 2 |
How Guidonia compares
- Tap water in Guidonia is 49 % harder than the median of the 629 cities we track in Italy (21.2 °fH).
- By hardness it ranks 78 of 629 in Italy (1 = hardest); 88 % of these cities have softer water.
- In Lazio it is number 21 of 54 cities; the regional median is 27.2 °fH.
- Nearest city with clearly softer water: Zagarolo, 19 km away (23.9 °fH).
- Nearest city with clearly harder water: Fiano Romano, 21 km away (62 °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 Guidonia
| Brand | Setting for this water |
|---|---|
| Bosch | H05 |
| Miele | 18 °dH |
| AEG / Electrolux | 4 |
| Beko | 5th |
| Hoover | S3 |
| 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 Guidonia water hard or soft?
It is very hard: 316 mg/L as CaCO₃ (18.5 gpg, 17.7 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Guidonia 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 Guidonia water?
18.5 gpg, equal to 17.7 °dH, 31.6 °fH or 316 mg/L calcium carbonate.
What dishwasher salt setting should I use in Guidonia?
For 316 mg/L (17.7 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Guidonia?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Acea Ato 2, qualità dell'acqua, scheda di zona (valori mediani) (2026-07). Method: figure published by the water supplier. Acea Ato 2, qualità dell'acqua, scheda di zona (valori mediani) · Outdated figure? Tell us