When It Rains, Sewage Often Pours Into Harbor

Besides flooding subways, the wild downpour this week provided a disconcerting glimpse into one of New York’s dirtiest environmental secrets: heavy rain regularly overwhelms the city’s vast sewage system and pushes polluted water into places it is not supposed to go.

New York has a storm water drainage system that was linked many years ago to the same pipes that carry wastes from homes and businesses. That, combined with the ever-expanding layer of asphalt and concrete that keeps rain from soaking into the ground, means that whenever it storms, some of the storm water and sewage in the 6,000 miles of sewer pipe in the city start to back up.

When that happens, millions of gallons of rainwater mixed with raw sewage are routed away from the city’s 14 sewage plants and toward a web of underground pipes that empty directly into the East River, the Hudson River and New York Harbor.

The backups could also prevent water from being drained from subway tunnels.

These events — called combined sewer overflows — have been recognized as a major environmental problem for decades. The city has been dealing with the issue in response to orders from the state and the federal government, but still has a long way to go.
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