The Metropolitan Waterworks and Sewerage System, 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. It split the water concession into an east and a west concession with Manila Water being awarded one contract and Maynilad Water Services being awarded the other.

Water privatization in Metro Manila began when the then President of the Philippines, Fidel Ramos, instructed the government in 1994 to solve what he called the water crisis in Manila by engaging with the private sector. In 1997, two concession contracts for the Eastern and Western halves of Metro Manila were awarded after an open competition. The concessions represent the largest population served by private operators in the developing world. Both winning companies, Maynilad Water Services in West Manila and especially Manila Water in East Manila, submitted bids with extremely low water tariffs. The tariffs proved to be too low to finance the investments needed to improve performance, especially after the East Asian financial crisis and the devaluation of the Philippine Peso.