It gathered more than 22,000 signatures calling for the city to hold a referendum.
Saskatchewan's Cities Act dictates a petition must have enough signatures to represent 10 per cent of a city's population to be deemed valid and binding.
That means the group would need 19,300.
River Water Watch spokesman Jim Holmes says water is a basic requirement and it should remain in public control.
Regina Michael Fougere has said the public/private partnership model is the best option for taxpayers.
"It's really a monopoly situation, there is one sewage plant and we pay for it through our water rates and that's effectively a tax, it's not optional to pay it, so there's no private market there, so it doesn't seem to make sense," Holmes said.