US President Barack Obama has declared a state of emergency in Flint, Michigan, where the water has become contaminated with lead.
The city’s water became contaminated after a change in supplier in 2014. Corrosive water leached lead from old pipes into the water supply.
The emergency declaration will unlock $5m (£3.5m) in federal funding.
Earlier in the week, Governor Rick Snyder had requested $31m from the federal government.
He said the need in the city of almost 100,000 people “far exceeds the state’s capability” and sought a disaster declaration.
But reports in Michigan said Mr Obama denied that request, that would have freed up more than the $5m, as such declarations are only made for natural disasters.
In October, testing revealed increased lead levels in water supplies and in children’s blood. Lead exposure can cause learning disabilities and behavioural problems in children.
Before then, residents had complained of discoloured water, bad smells and headaches and rashes from using the water from the city’s new supplier.
The city switched its water source from the city of Detroit to the Flint River in 2014. It has since switched back to Detroit’s water.
Michigan’s attorney general has said he will investigate the water crisis to see whether any state laws were violated.
The lack of clean water in Flint “is a human tragedy in which families are struggling even with the most basic parts of daily life”, said Michigan Attorney General Bill Schuette.
Mr Snyder has already declared an emergency in Flint due to the water situation. Local officials deemed it a public health emergency in October.
He has been criticised for his handling of the water crisis, with protesters calling for him to resign.
As a result of Mr Obama’s announcement, officials from the Federal Emergency Management Agency (Fema) will co-ordinate the response in Flint.
On Saturday, the singer Cher said she would donate bottled water to Flint residents, with some 180,000 bottles to be shipped.
“This is a tragedy of staggering proportion and shocking that it’s happening in the middle of our country,” she said.