N.J. Stat. § 58:5-26
After such hearing, the commission, if the water supply under its control is adequate for the supply of the applying municipality, may contract with the municipality for the supply to it of water at such price as shall impose upon the municipality an equitable share of the cost of constructing, acquiring and operating such supply; or the commission may allow the municipality to become part owner of the water supply plant controlled by the commission, or such part thereof as is necessary for the supply of the municipality by means of a contract whereby the municipality shall agree to pay to the commission its proportionate share of the cost of acquisition, construction and operation of the plant. Any money so paid to the commission by the municipality shall be paid over to the municipalities which have heretofore contributed to the cost of the water supply plant, upon such terms and in such proportion as the contracting municipalities have heretofore mutually agreed or as they shall hereafter mutually agree, and as shall be approved by the commission.
N.J.S. § 58:5-26