An eccentric millionaire is giving Manhattan back to the American Indians — at least his small part of it.

Jean-Louis Goldwater Bourgeois, 76, an architectural historian and activist for Native American causes, is in the process of transferring the deed of his $4 million, landmarked West Village house to a nonprofit controlled by the Lenape tribe, the original Manhattanites.

“I have a romance with the history of the city, and I have been generally appalled that the land that the city is on has been taken by whites,” he told The Post.

AS he traveled the world over the last several decades, from Africa to the American Southwest, Jean-Louis Bourgeois, an architectural historian, advocate for environmental rights and 21st-century hipster, had a vision of the often-forgotten role of water in human existence.

Now Mr. Bourgeois, with the assistance of his mother, the sculptor Louise Bourgeois, said he plans to bring that vision to life in an unusual museum dedicated to water in a small, sagging, historic wood-frame building he bought two weeks ago for $2.2 million.

Jean-Louis Bourgeois, left, with Phil Sauers, founder of the World Water Rescue Foundation, in front of 6 Weehawken St., where Bourgeois plans a new water museum. The plastic structure between them is a preliminary scale model by Bourgeois’s mother, the sculptor Louise Bourgeois, of a seven-story, subterranean “World Waterfall.” Sauers has accepted Bourgeois’s invitation to participate in the museum’s development. Bourgeois held a personal water jug from Mali called a sintal. Fittingly, it was raining.