The Passaic Valley Water Commission is asking the state for $26 million in the form of loan, a grant or both, to replace thousands of lead service lines linking water mains to homes and business.

Officials say the cost of the project, which could be higher depending on just how many lines will need to be replaced, could be borne at least in part by the owners of the properties served by the lines, which could number up to 15,000.

In addition to the line replacement money, the commission is also making a separate request that the state speed the approval process for replacing an historic but obsolete reservoir in Paterson. The reservoir project, estimated to cost another $26 million, would be an additional means of curbing lead levels in the commission’s service area, which includes 26 cities and towns in Passaic, Bergen, Morris, Essex and Hudson counties, with 750,000 people living and working there.

The water commission’s executive director, Joseph Bella, said the commission is seeking line replacement money in the form of a loan from the New Jersey Infrastructure Bank, a creation of the Murphy Administration to help public agencies update their facilities. “The way it all plays out, some of it could be a loan, some of it could be a grant,” Bella said.

The project would replace 7,900 known lead service lines in Passaic and Bergen Counties, plus as many as 7,000 more lines that the commission still needs to survey to determine whether they also need replacement, Bella said. He said the cost of the project could be higher than the $26 million now being sought, depending on the number of service lines that ultimately must be replaced.

Bella said a portion of all of the service lines involved — from the curb to the residential or commercial building — is the responsibility of the property owner, who will be assessed at least part of the cost of their line replacement, depending on how much of the Infrastructure Bank loan is forgiven.

The service line replacement is similar to a project now underway in Newark, which has drawn national attention in recent years for the lead in its drinking water. In two neighboring suburbs, Bloomfield has been gradually replacing its lead lines, while Belleville is planning its own replacement project.

As important as the loan application to replace the service lines, Bella said, the commission has asked the state Department of Environmental Protection to speed the historical review process necessary to replace the historic Stanley S. Levine Reservoir in Paterson, built in 1885 at the edge of what is now the Paterson Great Falls National Historical Park.

Bella said that because the Levine reservoir is an open-air facility, phosphates typically added to drinking water to combat lead contamination cannot be used by the PVWC. That’s because phosphates would essentially act as a nutrient in the exposed water, encouraging algae or bacteria growth, Bella said.

He said the two enclosed water tanks that would replace the Levine Reservoir would cost about $26 million, which could be financed by rate hikes or other means. The project, which has been opposed by preservationists, is part of a broader, $135 million plan to drain three reservoirs in the area, and and replace them with enclosed tanks.

Even after replacing the lead service lines, being able to add phosphates to the PVWC water supply is still a key to minimizing lead levels, Bella said, because of the presence of lead in other parts of the supply system, including soldered joints in household water pipes.

“Lead is still in houses,” he said. “Once you get the phosphates in the water, the lead goes way down.”

MORE: See our comic that draws out how lead got into drinking water across N.J.

Read more of NJ.com’s coverage of New Jersey water issues here.

Steve Strunsky may be reached at sstrunsky@njadvancemedia.com. Follow him on Twitter @SteveStrunsky. Find NJ.com on Facebook. Have a tip? Tell us. nj.com/tips