The Era in the north and the Cecina in the south are the two major rivers in the territory of Volterra.

The Era river with torrential features, is formed at the confluence of two streams ( the Era viva near Pignano and the Era morta , a torrent at Spicchiaola) originating from the springs at M. Voltraio.
The Era meanders through a varied landscape from the south-east to the north-west and is usually
full during the rainy season only to dry up almost completely during the hot summer.

The Cecina river, 74 kilometres long is in fact the largest river in the territory of Volterra.
The Cecina meanders through the Cecina valley gathering the torrents of Fosci, Sellate and Zambra.
In the summer the river is partly dry but during heavy rainfall, its wide basin and steep river beds
rapidly swell with the torrential flow of the incoming streams often causing high water levels.
Both the Era and the Cecina register a minimum water level in July and August and a maximum in November and March.