It originates, near some wind turbines, at what modern maps call Avonhead Cottage[1] south of Upperton just west of Longriggend.

[3] Some maps show a stream coming from Fannyside Lochs in North Lanarkshire, some 3 miles (5 km) east of Cumbernauld,[4] but that is not the Avon's source even if some water drains in a rivulet from there.

The Avon picks up the Shiellhill Burn close to Upperton, north of the sewage works and west of Easter Glentore Farm.

[8] After Avonbridge the Lin Mill Burn just after the start of the River Avon Heritage Trail.

[4] Like other rivers of this name throughout Britain, the name Avon simply means 'river', derived from Scottish Gaelic abhainn, or British (i.e. Old Welsh) afon.