Can Roof Water Drain Into Public Sewer System in NYC?

Roof water is directed into the public sewer system in NYC?

Maybe. But only if the public sewer is a combined system. About 60% of New York City has a combined sewer system.

In the 2018 IPC Section 1101.3 Prohibited drainage, it states, “Storm water shall not be drained into sewers intended for sewage only.”

But then in Section 1109.1, it says, “Where the public sewer is a combined system for both sanitary and storm water, the storm water shall be connected independently to the public sewer.”

About 60% of NYC has a combined sewer system.

Here are two good resources for NY home inspectors about NYC storm water and sewer systems:

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Much like Montreal, Ben.
This has to do with the treatment of sewer water, cost, and proximity to rivers.
Storm water can be distributed directly into rivers in many areas were as sewer/sanitary water requires treatment.
Ben Gromicko, “You’re The Best!”

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Thank you.

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Good information for inspectors.
I ask Realtors about gray water and sewer lines inspecting rural of around the greater islands of Montreal and Laval close to shore. Why? Should roof water drain Into Municipal roadway curbs or sanitary lines?

Good morning Ben,
The short answer is no but if your house or building has been connected that way (most are!) for a long time the buildings department will leave you alone, you are kind of grandfathered in but all new houses go by this;
All roofs , paved areas, yards, courts and courtyards shall drain into a separate storm sewer system, or a combined sewer system, or to an approved place of disposal.

Hello Robert

This is Shahid. To answer your question, I think in NY where I am from, most of the lots here are too small to include a Drywell or to drain away from the building. Some buildings do not even have a front yard. The only place for the water to go is in the sewer system. In Long island however, most houses do have big front yards.