GR20 safety and water: rescue, phone signal, water points

The GR20 is known as one of the most demanding treks in Europe. Corsica’s PGHM (the gendarmerie mountain rescue unit) carried out around 150 rescue operations between June and August 2025, the vast majority of them hiking-related. A few precautions are essential.

Emergency numbers

Every staffed refuge has an emergency phone and a medical kit during the season.

Water: a major concern

• The self-service water at the refuges is not tested: the Park recommends a filter water bottle and purification tablets.
• Stage 3 (Carrozzu – Haut-Asco): no water points at all, and the water in Lac de la Muvrella is not drinkable.
• Stage 2: no more water after the spring above the stream until Carrozzu.
• Stage 12 (Prati – Usciolu): water is scarce in July and August.
• Stage 16: fill your water bottles before the long descent.

Each stage page lists the water points recorded along the trail, with their position in kilometers.

Cell coverage

The cell signal is unreliable over much of the route, particularly near Ortu di u Piobbu, Carrozzu, Tighjettu, Ciottulu di i Mori, Manganu, Onda, Usciolu and Paliri. Phone charging is free in the refuges, except at Ortu di u Piobbu and Asinau.

Good safety habits

• Tell someone your itinerary and don’t hike alone.
• Set off early so you cross ridges and passes before the storms.
• Turn back if conditions deteriorate; skip the alpine variants in bad weather.
• Take out insurance that covers rescue and repatriation.