It rises in Bishop's Sutton and flows west for 6 km (3.7 mi) to meet the Itchen below New Alresford.

[6][7][8][9] This theory is supported by the fact that the Alre river name is recorded relatively late- first appearing indirectly as Alsford ryver in 1540 and then as Arre and Arle in 1586.

[citation needed] The river rises at a spring in the parish of Bishop's Sutton, 800 metres east of the old core of the village.

Flowing west, the lesser-populated north bank of the village has the first of its three little crossings, Water Lane, a ford.

[20] Its final section flows a couple of hundred metres south west through fields into the meandering course of the River Itchen.

Daniel Defoe mentions the river in his book A tour thro' the whole island of Great Britain.

There are several components that are used to determine this, including biological status, which looks at the quantity and varieties of invertebrates, angiosperms and fish.