What Is a DEP Filing?

DEP Filing: The Definition

A DEP filing is an application submitted to the New York City Department of Environmental Protection (DEP) — the city agency responsible for the drinking water supply, the sewer system, and local environmental controls. When a project connects to or alters the public water or sewer system, installs a device that protects the water supply, or manages stormwater, DEP is the agency that reviews and approves the work.

It's important not to confuse the city DEP with the state DEC. The New York State Department of Environmental Conservation (DEC) is a separate state agency that handles statewide environmental matters such as wetlands, hazardous materials, and air and water quality permits. DEP is the city agency that runs New York City's water and sewer infrastructure. A project can involve one, both, or neither — but the filings go to different places.

If your project needs a DEP application prepared and filed, see our DEP Filing service, part of our full NYC agency filings practice.

When a DEP Filing Is Required

A DEP filing is generally triggered whenever a project touches the public water or sewer system or the city's environmental controls. Common triggers include:

• New or altered sewer or water connections — tying a building's sanitary and storm service into the city mains, or modifying an existing connection.
• Water main taps and extensions — creating a new tap into a water main or extending a main to serve a property.
• Backflow prevention devices — installing a device that keeps contaminated water from flowing back into the public supply, plus the annual test filed each year.
• Grease traps and interceptors — required for many restaurants and food-service establishments before waste can discharge to the sewer.
• Stormwater and site drainage — plans that show how a site handles stormwater and connects drainage to the city system.
• Dewatering — controlling and discharging groundwater during excavation and construction.

Types of DEP Filings

DEP handles several distinct application types. Most projects need one or more of the following:

How the DEP Filing Process Works

Most DEP filings follow a similar path from preparation to sign-off:

• Licensed master plumber — Sewer, water, and backflow filings must be prepared and certified by a licensed master plumber, who develops the connection or device drawings.
• Application submitted to the borough office — The package is filed with the DEP borough office that covers the property, which reviews the plans against city standards.
• Review & objections — DEP examines the submission and may issue objections. An incomplete package is the most common cause of delay, so responses need to be prompt and complete.
• Approval — Once objections are cleared, DEP approves the filing, authorizing the connection, device, or plan.
• Inspection & sign-off — Where required, DEP inspects the completed work and issues final sign-off confirming the connection or device was built and installed as approved.

DEP and the Department of Buildings (DOB) are separate agencies with separate approvals, but they are closely linked on most construction projects. DOB governs the building work; DEP governs how that building connects to the water and sewer system.

Crucially, DOB sign-off can depend on DEP approval. A building permit or final sign-off may be held until the corresponding DEP approval — for the sewer/water connection, backflow device, or drainage plan — is on file. That's why the two tracks need to be coordinated: a stalled DEP filing can hold up the entire DOB permit.