New York State law requires certain properties and businesses to install water backflow prevention devices as cross connection control.

Your drinking water is pushed from the city's water main into your property's plumbing by pressure. It should flow in one direction. Pressure changes in pipes can cause water to flow backwards into city water lines. This could contaminate the public water supply.

These devices stop contaminated water from flowing backwards into the main water supply.

Failure to install backflow prevention devices could result in:

  • Fines
  • Disconnection of water service

The Department of Environmental Protection (DEP) can answer questions about these devices.

Online

Learn more about cross connection control and water backflow prevention.

By Email

Email connections@dep.nyc.gov.

By Phone

Call 311 or 212-NEW-YORK (212-639-9675) for help.

The following businesses must use backflow prevention devices, unless exempted:

  • Auto repair shops
  • Breweries
  • Canneries
  • Commercial car washes
  • Dye plants
  • Exterminators
  • Food processing plants and meat packers
  • Funeral parlors
  • Greenhouses
  • Hospitals, clinics and laboratories (including veterinary hospitals)
  • Large residential dwellings with water boilers that use rust-inhibitors or other treatment chemicals ("treated water boilers")
  • Laundries and dry cleaners
  • Medical and dental offices
  • Metal platers
  • Photo-processing facilities
  • Paper processors
  • Premises with multiple water service lines
  • Premises with roof tanks and elevated storage lines
  • Sewage treatment plants or handling facilities
  • Shipyards and marinas
  • Tanneries

To install a backflow you must hire either a:

  • Professional Engineer (PE), or
  • Registered Architect (RA)

The PE or RA must follow the procedures in the DEP's Cross-Connection Brochure. The brochure, required documents, and forms are available online.

Learn more about cross connection control and water backflow prevention.

Exemptions must be filed on behalf of the property owner by either a:

  • Professional Engineer (PE), or
  • Registered Architect (RA), or
  • Licensed Master Plumber (LMP)

To file:

  1. All required info must be in a typed letter on letterhead
  2. The letter must state that all necessary exemption conditions have been met
  3. It must be sent to the DEP for approval

An exemption guide is available online.

Learn more about cross connection control and water backflow prevention.

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