The US National Guard is boosting its presence in Flint, Michigan, as part of efforts to help deal with the city's drinking water crisis.
The state said about 70 guard members will be stationed in Flint, more than double the earlier number in place.
State officials said teams visited nearly 5,000 Flint homes on Sunday, providing free bottled water, filters, replacement cartridges and water testing kits.
To improve water testing, the state said residents may drop off samples using official kits at five designated sites.
The drinking water became contaminated after Flint switched from the Detroit water system to the Flint River as a cost-cutting move.
The corrosive water lacked adequate treatment and caused lead to leach from old pipes.
On Saturday, US president Barack Obama signed an emergency declaration over the situation.