Château d'Eau (French pronunciation: [ʃɑto do]; literal translation: Water Tower) is a station on Line 4 of the Paris Métro.

Located in the 10th arrondissement, it features two entrances by Hector Guimard which were classified as a monument historique on 29 May 1978 by the Ministry of Culture.

The road, in turn, received its name from the square to the east of the current station that was known as the Place du Château d'Eau until 1879.

Château d'Eau station opened on 21 April 1908 as part of the initial stretch of Line 4 from Porte de Clignancourt in the north to Châtelet in the heart of Paris.

This is in part due to the cut-and-cover nature of the Paris Métro, in which a major thoroughfare was dug up from street level and then re-covered after the tracks and stations were built.