Castro highlighted that Brazil's president is in charge of naming the development bank's new head.
The São Paulo state water utility's costs and expenses increased by more than revenues in the period.
The water utility in the Brazilian state company is turning its focus to projects in small cities.
Projects will be eligible to receive loans from state-run banks BNDES and Caixa Econômica Federal.
The sewage treatment project already has a proponent-in-waiting, but Peru's government hopes to drum up competing bids.