Chapet is a commune in the Yvelines department in the Île-de-France region in north-central France, about 16 km east of Mantes-la-Jolie. I…Chapet is a commune in the Yvelines department in the Île-de-France region in north-central France, about 16 km east of Mantes-la-Jolie. It is on the Normandy motorway. The commune's neighbours are Verneuil-sur-Seine to the northeast, to the east is Vernouillet, with Morainvilliers to the southeast, Ecquevilly to the southwest, and to the northwest is Les Mureaux.