Mayor Karen Weaver has told the Environmental Protection Agency that more corrosion control studies have to be done and Flint will need more than two years before the city can begin to supply its own water.
Extensive work, including chemical mixing and filtration, also is needed at the city's water treatment plant.
Flint switched from Detroit water to the Flint River in 2014 to save money, but corrosive water caused lead to leach from aging pipes into homes.
Flint has switched back to water from Detroit's system. The city is expected to switch to a regional pipeline late next year and treat the water itself.
More details here.