The town of Jouars-Pontchartrain is located 35 km west of Paris, 18 km west of Versailles and 22 km from Rambouillet, on a buttress which delimits the western end of the plain of Versailles and at the foot from which begins the plain of Montfort-l'Amaury. Its territory is irrigated by the Mauldre whose south-north oriented course follows the eastern limit of the town and receives in the park of the Château de Pontchartrain the Élancourt brook, a diversion of which feeds its pond. This brook, oriented east-west, is enlarged a little upstream by the Maurepas brook which joins it at Chennevières.
Pontchartrain, in the north of the municipal territory, heart of the municipality, where are located, around the town hall, the Saint-Lin church and the Saint-Louis hospital, the majority of local shops and most of housing.
Chennevières, south-east of Pontchartrain and adjoining it. It is a residential and old hamlet, formerly a humid places where the culture of hemp prospered.
La Richarderie, to the east of Chennevières and adjoining it, is a semi-residential, semi-rural hamlet.
Jouars, away to the south of Pontchartrain, has a church and has only a few dwellings and rural farms.
Ergal, in the far east and on the edge of the municipal territory is adjoining the hamlet of Launay in the municipality of Élancourt, half-residential, half-rural.
Les Mousseaux, south of Jouars, on the edge of the municipal territory and adjoining the hamlet of Villeneuve (parc aux Loups) in the municipality of Maurepas, is half-residential, half-rural with a few small craft businesses.
La Dauberie, a very wooded residential area, is on the edge of Saint-Rémy-l'Honoré.
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