said it was "inexplicable and inexcusable" that the city of
has been drinking lead-polluted water since April 2014, as the embattled governor of Michigan struggled to stem the crisis.
Flint's tap water has been
, and the liquid flowing from the pipes is a thick brown colour. The city's 100,000 residents have to buy bottled drinking water, and some parents are bathing their children in mineral water after reporting skin rashes from the taps.
Rick Snyder, the governor, released hundreds of pages of emails relating to his handling of the crisis in a bid to show transparency and leadership.
But among the emails was a conversation with Mr Snyder's chief of staff, expressing concern that the issue could become "a political football" without yielding suggestions as to how to solve it.
A forklift driver moves a pallet of water in a warehouse in Flint Photo: Carlos Osorio/AP
The saga began when the cash-strapped city, under a state-appointed emergency manager, switched its source from Lake Huron, which Detroit uses, to Flint River water, in a bid to save money.
"What is inexplicable and inexcusable is once people figured out that there was a problem there and that there was lead in the water, the notion that immediately families weren't notified, things weren't shut down," said Mr Obama, who was in Detroit on Wednesday.
"If I were a parent up there, I would be beside myself that my kid's health could be at risk."
Mr Snyder has been facing protests, lawsuits and calls for his resignation.
He apologised to the city's residents on Tuesday and called for the state to spend $28 million on fixing the situation.
The US Environmental Protection Agency, while saying it was reviewing its handling of the crisis and could have acted faster to inform the state of what measures it should take, also blamed the state on Tuesday. It said the agency's oversight was hampered by "failures and resistance at the state and local levels."
Flint did not return to Detroit water until October 2015 after tests showed elevated levels of lead, which can cause brain damage and other health problems, in Flint tap water and in some children. Corrosive water from the river, known locally as a dumping ground, caused more lead to leach from Flint pipes than Detroit water did.
Flint resident Andrew Watson, right, drops to the floor in tears as Flint Police stand guard at the city council chamber doors, not allowing city residents to listen to Michigan Gov. Rick Snyder Photo: AP
"This is something nobody should have to deal with. Everybody should have clean water," said Karen Weaver, mayor of Flint.
In a speech on Tuesday, Mr Snyder said federal, state and local leaders had failed residents. He asked Michigan to authorise spending on diagnostic tests, health treatment for children and adolescents, replacement of old fixtures in Flint schools and day care centres and a study of the city's water pipes.
He also released 274 pages of Flint-related emails from 2014 and 2015, ranging from press releases to staff memos and planning notes.
"We can't tolerate increased lead levels in any event, but it's really the city's water system that needs to deal with it," wrote Dennis Muchmore in September 2015.
He said the state Department of Environmental Quality and the Department of Community Health "feel that some in Flint are taking the very sensitive issue of children's exposure to lead and trying to turn it into a political football, claiming the departments are underestimating the impacts on the populations and particularly trying to shift responsibility to the state."
As many as 9,000 children may have suffered lead poisoning.
Several lawsuits have been filed in the case. The latest, on Tuesday, asked a judge to stop Flint from issuing "shut-off notices" to residents who are still receiving bills for water declared undrinkable
