The Brazilian company's investments increased 70% in 2018.
Confidence within the sector is at its lowest since October 2018.
The special purpose companies were auctioned by the Brazilian holding company last September.
Brazil's federal oil firm tried to sell Liquigás in 2017 but antitrust regulator Cade refused to approve the operation.
Contracts awarded by the water utility between 2012 and 2016 are being investigated.
Though paying twice the Brazilian government's minimum price, Rumo still made a bargain, the railway watchdog's labor union said.