A utility official in Flint, Michigan, says the test of the temporary pumping system that will increase chlorine levels in the city's drinking water went well.
The U.S. Environmental Protection Agency had recommended that Flint install a system by Friday. Utilities chief JoLisa McDay says full operations are expected to start Monday.
Flint was under state management when it switched from Detroit's water system in 2014 to the Flint River to save money. That water was not treated with anti-corrosive chemicals, causing lead to leach from old water lines.
The city is now back on Detroit water.
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The EPA has said more chlorine is necessary during warm weather, but Mayor Karen Weaver had stressed the city didn't want to create more problems by adding chemicals too quickly without proper guidance.