“We’re living off the legacy not of our parents but of our grandparents,” he said.

The new state act, which spans five years, will among other things provide $1.5 billion in grants for water infrastructure improvements, $75 million in rebates to help homeowners replace septic systems and $110 million to protect land in watersheds. The money significantly expands a similar state infrastructure fund that over the last few years made $400 million available to communities.

In addition to the new water infrastructure financing, the state budget allotted $40 million to build two sewer systems in business districts on the North Shore in Suffolk County. And there was $5 million for Suffolk County and the Center for Clean Water Technology at Stony Brook University to develop new methods of removing contaminants from drinking water.

While it was one of the more significant investments to emerge from the state budget, some say it should be viewed as a down payment. Steve Englebright, a state assemblyman who heads the Environmental Conservation Committee, has said $80 billion to $100 billion is required to address the state’s aging water infrastructure.

On Long Island, which is already grappling with hazardous waste at scores of active Superfund sites, the geology poses special challenges. With scant wastewater treatment, Suffolk County sits atop an aquifer that provides virtually all of its drinking water, and the sandy soil allows nitrogen to seep into it.

Nassau County, just west of Suffolk, has many more homes using sewers than Suffolk, where 75 percent of the population relies on septic systems. The main reason that a county as populous as Suffolk has remained on septic systems, county officials say, is the legacy of the last attempt at installing a system — the infamous Southwest Sewer District.

The sewer system, covering parts of the towns of Islip and Babylon, was eventually built. But the project, which started coming on line in 1981, became so mired in corruption, delays and cost overruns that it spooked future elected officials.