Landfill leachate disposal at sewage treatment plants occurs throughout New York State, and some of the state’s most important drinking water sources receive the largest volumes of leachate 

In our earlier research, we mapped available data to show how landfill leachate moves from landfills to municipal sewage treatment plants and into the Hudson and Mohawk Rivers. That analysis found that approximately 89 million gallons of landfill leachate were discharged each year into these rivers between 2019 and 2023. The Hudson and Mohawk study demonstrated how gaps between solid waste, wastewater, and drinking water regulations allow this practice to continue unnoticed.

This report expands the analysis statewide to understand the full scale of the Leachate Loophole. By mapping transfers of landfill leachate to sewage treatment plants across New York State, we document where leachate is entering waterways and which drinking water sources may be affected. 

Beyond the numbers, our review revealed that leachate record-keeping badly needs modernization, transparency, and improved oversight. The results presented here are our best estimates of leachate flows based on information available publicly and provided to us by municipalities. However, some of these sources contained serious discrepancies and gaps. Our main purpose in presenting these statistics is to shed light on the practice of leachate disposal, and the systems through which it operates.

Key Findings

• Landfills sent more than half a billion gallons of leachate to New York State municipal sewage treatment plants each year from 2019-2023.
• At least seventy-five active (30) and inactive (45) landfills disposed of leachate at New York State municipal sewage treatment plants.
• Municipal sewage treatment plants that accepted leachate discharged into 24 water bodies in New York State and one in New Jersey.
• Approximately 167 million gallons of leachate—one-third of the total—ended up in rivers and lakes officially designated as drinking water sources. These waters supply drinking water to nearly 2 million New Yorkers.
• The four rivers and lakes that received the largest leachate volumes—Lake Ontario, Hudson River, Niagara River, and Mohawk River—are also major drinking water sources.
• In New York State, leachate is being discharged into rivers which supply drinking water to New York City, Baltimore, Philadelphia, and other Pennsylvania municipalities.
• Many chemicals that have been banned or phased out of commerce due to ecological and human health risks—including metals, pesticides, and per- and polyfluoroalkyl substances (PFAS)—continue to appear in landfill leachate because they persist in waste deposited decades ago.
• There were serious  discrepancies between leachate disposal data reported by landfills and that reported by sewage treatment plants, including over 100 million gallons of leachate that landfills reported and were not accounted for by any municipal sewage treatment plant in our study.
• Just three private companies, each earning $2-$25 billion in 2025 revenues, managed half of the leachate generated by active New York landfills.