N.J. Stat. § 40:63-68: Contracts with other municipalities generally

The governing body of any municipality may contract with the governing body or bodies of one or more other municipalities:

a. To construct or purchase any works, system or plant, or any portion thereof, at their joint cost, within or without the territorial limits of the contracting parties; or

b. To receive and care for, or dispose of, the sewage of such other municipality or municipalities; or

c. To have its sewage received and disposed of by any other municipality or municipalities.