State Senate Republicans on Sunday proposed spending nearly $8 billion on clean water and sewer projects, including a $5 billion infrastructure bond and creation of an institute to set state standards for unregulated contaminants.

Senate Majority Leader John J. Flanagan (R-East Northport) said contaminated water supplies and infrastructure failures jeopardize public health and constrain the economy across the state.

“The Senate’s budget plan takes bold and necessary steps toward providing the resources our state desperately needs to ensure the long-term safety of our drinking water and wastewater infrastructure,” Flanagan said in a statement issued Sunday.

The proposal is part of the Senate Republicans’ “one-house budget” proposal that will be released in full on Monday. It would address the decades-old issue of septic tanks on Long Island that threaten drinking water supplies and surface waters, according to a Senate report released last year after a series of public hearings chaired by Sen. Kemp Hannon (R-Garden City). The report estimates that 360,000 homes in Suffolk County are not connected to sewers and the state needs to spend about $80 billion over 20 years to adequately upgrade the water infrastructure.

The Republican state budget plan includes support for $2 billion in clean water funding proposed in Gov. Andrew M. Cuomo’s executive budget to be used in the short term. The $5 billion Clean Water Bond Act would need to be approved by voters, likely in 2018, Senate Republican spokesman Scott Reif said. Which projects would be funded and how money is divided by region has yet to be determined, he said.

Senate Republicans also proposed a Drinking Water Quality Institute made up of public health experts, scientists and water providers to help set standards on unregulated contaminants.

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The Assembly’s Democratic majority will release its one-house budget on Monday. A source had told Newsday that it will include at least $2 billion, probably in a bond act, to address water quality concerns statewide.

Flanagan, Assembly Speaker Carl Heastie (D-Bronx) and Sen. Jeff Klein (D-Bronx), leader of the Senate’s Independent Democratic Conference, are to begin budget negotiations this week. They seek to have a budget agreement by the April 1 deadline on a spending plan that is expected to exceed $162 billion.

“This has the potential to be the year of water,” Adrienne Esposito, executive director of Citizens Campaign for the Environment, said Sunday. “The Senate is listening to the public outcry to protect our public resources.”

She said $1 billion out of the $5 billion should be earmarked to help Long Island homeowners replace old septic systems with those that remove nitrogen from the water and help other homeowners connect to existing sewer districts. Nitrogen is a key pollutant in Long Island’s waterways.

Suffolk County Executive Steve Bellone last year proposed a fee on water usage to pay for clean water projects in the county, but the idea was rejected in the senate.

Cuomo spokesman Leo Rosales said the governor welcomes the support for his $2 billion water initiative and would review the Legislature’s proposal.