The bank will provide funds for pre-investment studies for a wastewater collector and treatment plant in the central district.
Neither the Colombian city's government nor the local water utility have more resources to repair a section of the aqueduct system that was severely damaged by a landslide last week.
The proposal, which is different from bills under study to create a water framework, will be taken up by different parliamentary groups in the coming days.
The funds will be used in the ongoing project to rehabilitate Las Pavas plant, the country's largest potable water source.
Mauá's utility must now pay around US$456,000 to São Paulo state water utility Sabesp.
The order benefits residents of a certain district in Goiás state capital Goiania.
Two major candidates said they would scratch plans for in the water utility's privatization.