US President Barack Obama has pledged his support to the Michigan city beset by a water contamination crisis, saying Flint had been "short-changed".
Speaking from nearby Detroit, he said: "If I were a parent up there, I would be beside myself that my kid's health could be at risk."
The city's water became contaminated when lead leached from old pipes after a change in supplier in 2014.
Since then, residents have complained of bad smells, headaches and rashes.
Unable to drink tap water, the National Guard has joined volunteers in distributing lead tests, filters and bottled water.
Michigan Governor Rick Snyder has faced calls to resign over the way he has handled the crisis.
On Wednesday he released a batch of emails from 2014 and 2015 concerning the issue.
One email suggests that a day after doctors reported high levels of lead in local children, one of the governor's top advisers told him city officials, not state officials, had to "deal with it".
The switch to a river water source was a money-saving move when the city was under state financial management.
The water from Flint River stripped lead from the pipes and into the supply.
Lead exposure can cause learning disabilities and behavioural problems in children.
Last week, Mr Obama declared a state of emergency in Flint, which is predominantly an African-American, working-class city.
That declaration brought $5m (£3.5m) in federal aid but was far short of the $31m requested by Republican governor Mr Snyder.
A day after meeting Flint Mayor Karen Weaver, the president said: "I told her we are going to have her back and all the people of Flint's back as they work their way through this terrible tragedy.
"It is a reminder that we can't short-change the basic services we provide to our people."
Mr Snyder has urged Mr Obama to class the crisis as a federal disaster, saying its severity poses an "imminent and long-term threat" to residents.
By classing it as such, on the same level as natural disasters, the city would be able to get much more federal aid.
In an interview this week, Mr Snyder admitted it was a disaster but denied it was his "Katrina moment" - a reference to the much-criticised response of President George W Bush to the hurricane that devastated New Orleans in 2005.