Estuar replaces Rafael Alunan III, a former Secretary of Interior and Local Government, who will be retained as a consultant to the Lopez Group.
Alunan also retains the presidency of First Philippine Infrastructure Development Corp. and directorships in infrastructure-related businesses.
Prior to his appointment, Estuar was president of First Balfour Beatty, the construction arm of the Lopez Group.
Benpres Holdings Inc. chairman Oscar Lopez said "the Lopez Group would like to maximize the benefit of the experience of Alunan, particularly in political and security concerns."
Maynilad is 59 percent owned by Benpres, the local flagship of the Lopez family, while about 20 percent is owned by Ondeo, a French multinational affiliated with Suez Lyonnaise des Eaux and another 20 percent by Lyonnaise Asia Water Ltd.
Lopez said Estuar is mandated to assure the continued provision of adequate service to the millions of people dependent on the water services of Maynilad simultaneous with its financial rehabilitation.