Changewater is an unincorporated community located within Washington Township, in Warren County, in the U.S. state of New Jersey.

The community was named for its location at the confluence of the upper and lower branches of the river.

[4][5] One of the early iron furnaces in the county—known as the Changewater Forge—was established here in the mid-1700s by Mark Thomson [3] and later purchased by a well known local Van Leer family.

The crime attracted widespread publicity, and in 1845, two men were convicted and hanged at the Warren County Court House.

[3] In 1874, the village consisted of a looking glass and picture framing factory, a store and post office, a grist mill, and eight residences.