The protesters said the sale and privatization of PGW would increase gas prices, deeply affecting, or even eliminating, assistance programs for low-income families and senior citizens.
"Privatization is a way to take the city's debt and take it to consumers," said protester Jim Moran, 74, of the Northeast.
Council President Darrell Clarke told the protesters that the plan is the "most significant transaction in the city of Philadelphia" but took a petition and listened to their concerns.
"No action should be taken until all factors are taken into consideration," Clarke told the group.
Suzanne Biemiller, the mayor's first deputy chief of staff, said the protesters were "misinformed" and were protesting "for false reasons."
She said that UIC would be contractually obligated to continue the programs benefiting low-income families and senior citizens. Biemiller also said the plan eventually would lower gas prices for residents and would create more unionized jobs by replacing infrastructure, some of which is up to 150 years old.
The plan could add as much as $631 million to the city's pension fund, the Mayor's Office said.