Frequently asked questions

What is it and where does it come from?

We all create sewage sludge. Anything flushed down the toilet or dumped down the drain in homes, schools, hospitals, streets, businesses and industry flows through the sewer system to sewage treatment plants. Treatment plants clean the liquid part of the sewage and attempt to remove some of the toxic metals, excess nutrients and pathogens from wastewater. The resulting liquid is discharged into river, lakes and streams as effluent. The leftover solids and semi solids that are “filtered” from wastewater make up the “sewage sludge.”

After “treatment” where does sewage sludge go?

Used water goes into New York City’s extensive wastewater treatment system. This amazing network system that cleans our wastewater consists of: over 6,000 miles of sewer pipes; 135,000 sewer catch basins; over 494 permitted outfalls for the discharge of combined sewer overflows (CSOs) and stormwater; 93 wastewater pumping stations that transport it to 14 wastewater treatment plants located throughout the five boroughs. The New York City Department of Environmental Protection (DEP), Bureau of Wastewater Treatment (BWT) is responsible for the operation and maintenance of all facilities related to the treatment of sewage. The Bureau of Wastewater Treatment has 1,900 employees, an annual operating budget of $262 million, and an annual capital budget of $114 million. With these resources, the 1.4 billion gallons of wastewater discharged by eight million residents and workers in New York City each and every day is processed at the treatment plants. After the treatment process is completed, the plants release highquality, treated wastewater, called effluent, into the waterways surrounding New York City.

How You Can Make a Difference?

Conserve water: There are many simple ways to use less water every day, such as taking shorter showers, turning off the faucet when you brush your teeth or shave and fixing leaks. Keep hazardous substance out of the sewer system: Reduce the use of hazardous household products. Never pour hazardous materials down a sink or toilet or dump them into a storm drain. Save hazardous wastes for a DOS household waste collection day or wrap them safely in plastic and call the DOS for instructions. And remember, it’s against the law to dump used motor oil down a storm drain. It should be taken to a gasoline service station for recycling.


The New York City Department of Environmental Protection

The New York City Department of Environmental Protection distributes publications about wastewater treatment, the water supply system, water conservation and other environmental issues. For further information, or to obtain publications, or report water main breaks, streets leaks, open fire hydrants, sewer or storm drain backups and other problems, contact New York City’s 24-hour Citizen Service Center at 311. You may also visit the New York City DEP web site at:

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