The local chalk aquifer has excellent storage and filtration and the river has long been used for drinking water.

The settlement of Itchen Abbas, before its abbot's ownership, is transcribed by early Middle English orthography which used the letter c followed by e or i to denote the /tʃ/ sound and an e invariably after an n to avoid those down strokes being ambiguous thus, as Icene in the Domesday Book of 1086.

The river then carves its way west passing the villages of Avington, Itchen Stoke, Itchen Abbas, Martyr Worthy, Easton, and Abbots Worthy; to enter the cathedral city of Winchester it crosses Winnall Moors to turn south for its remainder.

[14] Monks Brook flows into the Itchen at Swaythling, and the river then passes under Woodmill Bridge and becomes tidal.

From seaward they are:[21] Above Northam Bridge, the limit of navigation for masted craft, are the Vespasian Road boatyard and numerous small establishments.

The SSSI covers the river and its banks, with fen, flood meadows, wet woodland and swamp.