The River Erewash is a river in England, a tributary of the River Trent that flows roughly southwards through Derbyshire, close to its eastern border with Nottinghamshire.

The Trent is the third longest river in the United Kingdom. Its source is in Staffordshire, on the southern edge of Biddulph Moor. It flows through and drains the North Midlands into the Humber Estuary. The river is known for dramatic flooding after storms and spring snowmelt, which in the past often caused the river to change course.