Flood and landslide risk in Italy: how to check a house

Italians call it rischio idrogeologico: the risk of landslides and floods. For a house you check it on the address, using two separate maps: the flood-prone areas and the landslide hazard zones, both drawn by the river basin district authorities and combined for the whole country by ISPRA (the Italian Institute for Environmental Protection and Research) on its IdroGEO platform. It is worth adding the inventory of landslides that have already happened. Knowing that the comune (the municipality) is "at risk" tells you little: almost every Italian comune is, and two streets in the same town can be in opposite situations.

How widespread it is in Italy

ISPRA's latest report on hydrogeological instability, the 2024 edition presented on 30 July 2025, finds 94.5% of Italian municipalities exposed to landslides, floods, coastal erosion or avalanches. The landslide hazard zones in the river basin plans cover 69,500 square kilometres, 23% of the country, up from 55,400 in 2021: the increase comes mostly from more detailed studies, and the high and very high hazard zones grow from 8.7% to 9.5%.

5.7 million people live in areas at risk of landslides, 1.28 million of them in the most dangerous zones, which also contain 742,000 buildings. The national landslide inventory lists more than 636,000 events, and about 28% of them are rapid movements, the most dangerous for people. For floods the report points to the new maps of the flood risk management plans, due in 2026 with the third cycle of the EU Floods Directive.

These figures describe the country. For a house, what counts is the plot and the hundred metres around it.

Floods and landslides: two maps, two scales

Flood-prone areas have three hazard classes, P3, P2 and P1, which say how often water can be expected: on average once every 20 to 50 years in frequent-flood areas, once every 100 to 200 years in less frequent ones, and only in extreme events in rare ones. How to read them for an address is explained in How to tell if a house in Italy is in a flood zone.

For landslides the scale runs from P4, very high hazard, to P1, moderate, plus attention areas where a movement has been reported but not yet studied. Next to the plan zones there is the IFFI inventory, which maps the outline of recorded landslides: a plot can sit outside every hazard zone and still have a recorded landslide two hundred metres away. The details are in How to tell if a house in Italy is at risk of landslides.

The two maps do not add up to a single score. A house on a plain near a river may only have a water problem, a hillside house only a slope problem, and the questions to ask are different.

Hydrogeological risk and the hydrogeological restriction

Listings often mix up two different things. Hydrogeological risk is the likelihood that landslides or floods hit a place, and it is set out in the river basin authorities' plans (the PAI and the flood risk management plan), which also limit new buildings and extensions.

The vincolo idrogeologico, the hydrogeological restriction, comes from a 1923 law (Royal Decree 3267/1923) and mainly covers woodland and hill or mountain land: anyone who wants to dig, level the ground, clear trees or build needs prior authorisation from the body the Region designates. It does not say the land is dangerous; it says that working it badly could make it so. For land it appears on the planning use certificate; for a house you ask the Comune's technical office, because it affects extensions, pools and retaining walls.

What to check before you buy

The first step can be done from home: put the address on both maps. If the plot falls in a flood-prone area or a landslide hazard zone, or one lies a few metres away, the questions change.

Ask the seller whether cellars, garages and ground floors have ever flooded, whether cracks have appeared in walls or floors and when, and whether any work has been done to keep water out or stabilise the ground, with the paperwork. In a block of flats, ask the building manager (amministratore) about water or subsidence claims and the insurance in place. Ask the Comune whether the river basin plan or the local plan limits work on the plot, and whether any protection works are planned in the area.

Then there is insurance. For households, cover against landslides and floods is not compulsory; the obligation in Law 213/2023 applies to businesses. If you want it, you add it to the home policy, and the price depends on exactly these maps: how to weigh the premium against the expected damage is in Floods and earthquakes: how much a house is at risk and what insurance covers.

What the report shows

Type the address: straight away and free of charge you see the liveability index of the area, which also takes landslides, floods and earthquakes into account. With a critical natural hazard the index cannot go above 60 out of 100, however good the services and green space.

In the full report, hydrogeological risk takes up four sections. The flood section says whether the cadastral plot falls in a P3, P2 or P1 area and how much of it is affected. The landslide section does the same with the plan zones and counts the recorded landslides nearby. The third uses satellite measurements to show whether the ground under the building is sinking (Ground movement), and the fourth estimates the average yearly cost of floods and earthquakes in euros (how we calculate it). The flood and landslide sections include a map one kilometre across, and every section cites its source with the date of the data; the questions for the seller, the building manager and the Comune appear in the buying guide when they are needed. A real report with every section is in the full sample report.

For a plot of land you start from the sheet and parcel numbers or from coordinates: Check land in Italy before you buy it.

Sources and updates

The report uses ISPRA's national mosaics: version 5.0 from 2020 for floods, the 2024 river basin plans for landslides. They cover all of Italy with the same method, so every address is read on the same scale. For a check with legal standing you turn to the river basin district plan and the Comune's technical office, which also hold the latest updates. In violent storms the drains matter too: that is why the question about past flooding is always worth asking.

The figures on Italy on this page come from ISPRA's press release of 30 July 2025 on the report "Dissesto idrogeologico in Italia", 2024 edition. How we use these maps: Landslides and floods.

Frequently asked questions

How do I know if a town in Italy is at hydrogeological risk?

Almost certainly some part of it is: according to ISPRA, 94.5% of Italian municipalities have exposed areas. That is why the figure for the town says little. Look at the maps for the address, on ISPRA's IdroGEO platform or by searching for the house above.

Can I buy a house in an area at hydrogeological risk?

Yes, and many historic centres and lowland neighbourhoods are in one. The checks change: basements and cellars, past flooding or cracks, plan limits on future work, insurance. In a high-hazard area it is worth talking to a surveyor (geometra) or engineer before making an offer.

Is the risk stated in the purchase deed?

Usually not. The deed of sale (rogito) for a house does not list the hazard classes of the river basin maps: you need to check them beforehand. For land, the planning use certificate attached to the deed does give the plan zone and many restrictions, including the hydrogeological one.

Does the hydrogeological restriction stop you building?

Not on its own. It requires authorisation before excavation, earthworks, tree felling and building, so that the work does not make the ground unstable. Where building is banned, the ban comes from the hazard zones of the river basin plans or from the local plan.