The Bain rises in the Lincolnshire Wolds at Ludford, J. N. Clarke, (1990), The Horncastle and Tattershall Canal, Oakwood Press, a village on The Viking Way long-distance footpath, and flows through or past the villages of Burgh on Bain, Biscathorpe, Donington on Bain, Goulceby, Asterby and Hemingby before reaching the town of Horncastle where it is joined by the River Waring, which rises at Belchford, 5 miles to the north east of Horncastle.