The Metropolitan Waterworks and Sewerage System[1] (Tagalog: Pangasiwaan ng Tubig at Alkantarilya sa Kalakhang Maynila),[5] formerly known as the National Waterworks and Sewerage System Authority (NAWASA), is the government agency that is in charge of water privatization in Metro Manila and nearby provinces of Cavite and Rizal in the Philippines.

By 1909, the capacity of the system was increased to 92 million liters per day by the addition of pumping facilities and the construction of Wawa Dam.

RO functions as a collegial body composed of five members headed by the Director or Chief Regulator who has over-all responsibility for the operation of the office.

Any action or decision by the RO on substantive matters affecting the Concession Agreement requires at least a majority vote of three members.

The Chief Regulator chairs the meeting of the Regulatory Office and has the final approval over the hiring and dismissal of all professional staff of the RO.