HARRISBURG — Pennsylvania's sewer and water systems could get a substantial infusion of cash for repairs and upgrades if voters approve a Nov. 4 referendum on $400 million in new borrowing.

Experts say the money is sorely needed but amounts to little more than a drop in the bucket when it comes to the state's overall water and sewer infrastructure needs, which are estimated in the coming decades to reach tens of billions of dollars.

"A lot of it is 60 to 100 years old, it's dilapidated, it's collapsing," said Brenda Reigle, executive director of the Pennsylvania Utility Contractors Association in Harrisburg, whose members hope to perform much of the work. "It clearly needs to be replaced for the public health and safety."

The referendum directs that the money could also be used to build or repair stormwater runoff projects, address certain pollution controls and fund nutrient credits that would cut the environmental effect of agricultural chemicals.

As much as $200 million would be grants, with the remainder issued as low-interest loans. The project would be administered by the Pennsylvania Infrastructure Investment Authority, or Pennvest.

"There's certainly a long and ongoing need for this kind of funding, and we really do need this thing to pass," said Paul Marchetti, Pennvest's executive director.

Pennvest, which typically approves about $300 million a year in funding, puts higher priority on projects that improve public health, result in cleaner streams, revitalize communities or spur economic development through job creation, he said.

Marchetti expects some projects will help wastewater plants comply with federally mandated Chesapeake Bay cleanup standards. If the referendum is approved, decisions about who will get the money could begin to be made as early as January, he said.

A related bill that passed this summer will use revenues from slot-machine gambling to pay back $800 million in borrowing to repair and upgrade existing water and sewer systems, improve flood control and increase safety at high-hazard dams. The Commonwealth Financing Authority is currently developing a plan for how the grants will be handed out.

In July, Democratic Gov. Ed Rendell estimated the state's "unmet needs" for sewer and water projects at nearly $20 billion over the next 10 to 15 years. Reigle, with the state utility contractors' association, said a more accurate figure is $32 billion, at current prices, over the coming two decades.

Voters most recently approved borrowing for water and sewer projects in 2004, when they authorized $250 million. A $350 million bond issue in 1992 also passed.