Flood hazard (P1, P2, P3)

Flood hazard maps (pericolosità idraulica) show the areas that can be flooded by rivers, streams or the sea, in three scenarios set out by the EU Floods Directive:

• P3, high hazard: frequent floods, on average one every 20 to 50 years;
• P2, medium hazard: less frequent floods, on average one every 100 to 200 years;
• P1, low hazard: rare floods or extreme events.

The areas sit one inside the other: a P3 area is normally also P2 and P1. The official maps are in the flood risk management plans (Piani di gestione del rischio di alluvioni, PGRA) and in the PAI plans of the river basin district authorities; ISPRA combines them into a national map.

A house in a P2 or P3 area is not necessarily one to avoid, but it is worth knowing whether there are basement rooms, how high the ground floor is and whether the building has flooded before. Read more in Flood zones P1, P2 and P3.