Septeuil (French pronunciation: [sɛptœj] ⓘ) is a commune in the Yvelines department in the Île-de-France region in north-central France.

Septeuil is traversed by a small river, la Flexanville.

This waterway flows through eight other communes for a total distance of 11.1 kilometres (6.9 mi).

The Flexanville is a tributary of the Vaucouleurs which in turn empties into the Seine.

This Yvelines geographical article is a stub.