Since 2002, the Waikato River has been supplying around 75 million litres of water to metropolitan Auckland each day, meeting around eight percent of the area's needs in 2010/2011. The Waikato River is New Zealand’s longest river, running 425 kilometres from Mt Ruapehu to the Tasman Sea at Port Waikato.
Water from the Waikato River is treated at the Waikato Water Treatment Plant which is located in Tuakau. Environmental impact on the river is minimal because the water is abstracted just before it goes into the Tasman Sea. When there are low river levels, less than one percent of the river's volume will be needed. It is a drought resistant source that is not dependent upon rainfall, unlike the dams.