NEW CANAAN — Town leaders have signed off on a $25 million plan to bring natural gas to town.

First Selectman Robert Mallozzi III signed a deal with Eversource Tuesday — which will see a roughly $25 million investment from the energy provider — to bring in natural gas to the southern portion of town by 2018.

“What we’re looking at is a 2018-2020 type approach, with the first phase being approximately 4.5 miles, 4.7 miles from Stamford up Route 106, Farm Road, to connect the three schools,” Chris Luca, a project manager at Eversource, said of what he called “Phase One” of the project.

The nascent pipe would bring natural gas to New Canaan High School, Saxe Middle School and South Elementary School. The Waveny Health Center and the YMCA would also have the choice to come online.

In Phase Two, the pipe would continue up South Avenue into the southern portion of downtown and end near East School, according to Luca. Phase Three would see further expansion into residential neighborhoods.

“The Comprehensive Energy Strategy the governor’s put forward has given us the tools that we can use to get into a residential type setting. We’ve not been able to do that in the past, the economics never work, the revenue is far too little for the capital costs that it takes to get into those neighborhoods,” Luca said.

Prior to any building, Eversource will send “Energy Advisers” to neighborhoods affected to discuss the possibility of converting to natural gas. Homeowners would have to pay for conversion, but not for the installation of the main or for the service.

Both Mallozzi and Nick Williams were enthusiastic about the prospect of natural gas coming to town, with the latter calling it a “win-win.” Mallozzi was heartened by an expanded plan from years past.

“‘The fact that you folks came to us with this approval and it included a gas line all the way to east school, basically proved to me that you folks were going to be in a lot better position to expand natural gas closer to town because it was a much more robust outreach from Farm Road than it was two or three years ago,” Mallozzi said.

Selectman Beth Jones, however, expressed concern over the means by which natural gas is generally extracted and the recent fracking bans in states like New York and Maryland that seem to have caught on and could make supplies more scarce if more states follow their lead.

“I’m concerned down the road if we’re tied in to a 15-year deal where we’re required to get natural gas from you, and all of a sudden this starts being a situation where communities are suing the gas companies for polluting their groundwater and not being able to find things, and it gets more and more expensive, it could cost us a lot more in five years, or 10 years,” Jones said.

However, Luca noted that at any point during the 15-year contract, the town could review the economics of natural gas. Ferrelli added that only a small percentage of natural gas brought into Connecticut by Eversource comes from fracking, though he did not know the exact percentage.

“We have a very diverse portfolio of gas supply options that come into Connecticut and all of the northeast,” John Ferrelli, also of Eversource, said.

Mallozzi and Williams voted in favor of the deal. Jones voted against the gas line.; @justinjpapp1