A bill making its way through the Florida Legislature would allow the dumping of 5 billion gallons of treated sewage into the ocean every year, but save South Florida’s utility ratepayers at least $1.3 billion.

The bill would change a 2008 law that told utilities to completely stop flushing treated sewage into the ocean by 2025 to save coral reefs and marine ecosystems. A 2008 study by the Florida Department of Environmental Protection stated that “the weight of the evidence” showed the sewage was harming South Florida’s coastal marine life.

The new measure would allow utilities to pump a reduced amount of sewage into the ocean annually after the 2025 deadline: 5 percent of their annual sewage flow, which would total an estimated 5 billion-plus gallons a year. Right now, utilities pump about 71 billion gallons of treated sewage into the ocean a year.

All the sewage outflows affected by the bill, which is being considered by the Senate Budget Committee and has passed the House unanimously, are in Miami-Dade, Broward and Palm Beach counties. If the bill passes the committee, it will go to the full Senate for a vote.

“This is done in the best interest of the public, because it’s such significant savings to them,” said Alan Garcia, Broward’s water and wastewater director. “We’re still meeting most of the original goal.”

A University of Florida study in 2008 estimated that a household using an average of 7,500 gallons a month could pay an extra $19.80 per month if utilities have to shut down the pipes completely. That amount would go down if the bill passes, utility directors said.

Miami-Dade would save $820 million, Hollywood $160 million and Broward County $300 million, utility directors said.

The change to the 2008 law would not affect ratepayers in Palm Beach County as much. Delray Beach stopped dumping treated sewage into the ocean in 2008, and Boca Raton has reduced its ocean flow by half, and plans to shut down its pipe by 2015.

The original ban also aimed to prevent reusable water from being sent into the ocean.

It told utilities to find a way to reuse 60 percent of sewage for irrigation, watering lawns and even recharging the drinking-water aquifer. The current bill would not change that.

Divon Quirolo, founder of Reef Relief, an activist organization that pushed for the 2008 law, said he wonders whether utilities hope to erode the original law further.

She said the current bill also pushes back a deadline for utilities to have a plan for meeting the law’s requirements from July 2013 to October 2014. None of the three utilities pushing for the bill has gotten beyond the planning stages of their major water reuse projects over the past four years.

“They’re trying to delay, avoid and weaken,” Quirolo said.

The reason South Florida would save so much money if utilities could pump just 5 percent of sewage out to sea has to do with “peak flow events,” utility directors said — heavy rains or other events that suddenly overburden sewage-treatment systems.

Hollywood, Miami-Dade County and Broward County say they would have to build multimillion dollar wells to inject that “peak flow” into the ground unless they can just keep dumping into the Atlantic. They all have wells already to inject water into the ground, but would need to dig more to deal with peak flow.

While the amendment might be good news for anyone who pays a sewer bill in Broward and Miami-Dade counties, the change could be bad news for fish, coral and beaches.

Saving reefs and ecosystems was a major reason lawmakers passed the 2008 law.

Many scientists say the treated sewage, which contains chemicals from human pharmaceuticals and bathroom products, as well as nutrients that can cause algae blooms, has damaged the ocean environment off the South Florida’s coast.

The water contains no solids, but does not meet standards for watering a lawn or a field of crops.

“When the money isn’t there, the government wants to argue there’s no need for it,” said Matthew Schwartz, an environmental activist and executive director of the South Florida Wildlands Association. “Meanwhile, our coral reefs and marine ecosystems are being destroyed.”

The amendment was sponsored by representatives and senators from Miami-Dade and Broward counties.

Since Delray Beach shut off its pipe in 2008, it has had to open it again on three occasions.

They’ve pumped out about 1 percent a year out to sea, “nowhere near 5 percent,” said Dennis Coates, executive director of the city’s sewage plant.

Still, he does hope to keep pumping that much after the deadline. He said the option is useful for dealing with peak flows.

“This change allows us to not build a duplicate injection system that we would use a few days a year,” Garcia said. “That gives us a lot more efficiency for our dollars.”