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Wastewater Systems

Each day, ENV collects between 100-110 million gallons daily (mgd) of wastewater from the toilets, sinks and drains from homes and workplaces on Oahu. Through a system of 2,100 miles of pipeline, assisted by gravity and 70 pump stations, the wastewater is delivered to nine wastewater treatment plants, which are spread over the island and either owned or operated by the City and County of Honolulu.

In those plants, the wastewater is screened to remove debris, settled to remove organic solids, and treated to different levels - primary to tertiary - depending on the sophistication of the plant. After the wastewater is processed, the remainder is called effluent. ENV keeps close tabs on effluent through monitoring, discharging it back into the environment by ways of the ocean, reservoir or underground injection wells. In some cases, it is recycled and reused for irrigation and industrial purposes.

There are nearly 750 employees in ENV's divisions of Collection System Maintenance, Treatment & Disposal and Environmental Quality who protect public health and the environment through responsible management of wastewater.


Consent Decree

Wastewater Finances

Major Sewer Construction Projects

Customer Service

Treatment & Disposal

Collection System Maintenance

Environmental Quality

Last Reviewed: Thursday, January 23, 2014