Combining the Auckland Council's water company with its in-house drainage operation could save $30 million a year.
That is the biggest potential saving found in the first four reviews of the council operations, and could undo part of the amalgamation process of the city.
A high-level review of the city's so-called Three Waters stops short of a merger, but the mayor Phil Goff said that could be a future step.
Amalgamation created a council-owned company called Watercare to deliver water and treat sewage and wastewater, leaving drainage within the council. See more