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About Our Wastewater Plants

The City's nine wastewater treatment plants operate around the clock and employ more than 300 workers.  Wahiawa Wastewater Treatment Plant was the first, built in 1928, when Oahu's population was relatively low and life was agrarian.  Treatment plants were built in Kailua and Waianae in the 1960s as a growing economy increased the demands on wastewater capacity.  Individual systems were constructed along the coast. Septic tanks and cesspools were widespread.  As Oahu's population grew, so did national and state awareness of potential risks to the environment and public health.  The federal Clean Water Act passed in 1972 and was amended five years later.  Sand Island WWTP, Oahu's largest, opened in 1976 and Honouliuli WWTP followed in 1980.  Major upgrades to the system in the 1990s included a new surveillance system (SCADA) that brought centralized monitoring for the entire wastewater pumping and treatment system to the Sand Island Operations Control Center.

 View Full Map of Oahu Wastewater Management System 

Last Reviewed: Tuesday, May 10, 2011