Is Your Building Required to have a Backflow Prevention Device?

Backflow is when the water in a plumbing system flows in the incorrect direction. This is unsafe, due to water that has already been contaminated interacting with water that is meant to be clean. Prevention devices stop water that has already been used to flow in the wrong direction.

Where are backflow devices required?

The following are a list of places that must utilize backflow preventers on all water service lines to your building:

  • Metal plating, cleaning, processing or fabricating facilities
  • Photo-processing facilities
  • Laundries, dry cleaners
  • Commercial car washes
  • Greenhouses
  • Hospitals, Veterinary Hospitals, Clinics & Laboratories
  • Medical & Dental Offices
  • Funeral Parlors
  • Food processing plants & meat / fish packers
  • Dye Plants
  • Paper processors
  • Auto Repair Shops
  • Breweries
  • Tanneries
  • Exterminators
  • Large residential dwellings with water boilers that use rust-inhibitors or other water treatment chemicals
  • Sewage treatment plants or handling facilities
  • Premises with multiple water service lines;
  • Premises with roof tanks and elevated storage lines
  • Canneries
  • Slaughterhouses & Live Poultry Processing Facilities
  • Ice Manufacturing Facilities
  • Printing Facilities
  • Supermarkets
  • Premises with large boilers or chemically treated boilers
  • Warehouses (with toxic chemical storage)
  • Premises with Commercial or Public Kitchens
  • Premises with water cooled equipment or chillers
  • Premises with Groundwater Wells
  • Premises that Reuse or Recycle Water
  • Shipyards & Marinas
  • Schools & Colleges
  • Food Preparation Facilities
  • Nursing Homes
  • Barber Shops & Beauty Salons
  • Properties with in-ground irrigation sprinklers

If you have received an exemption from the Department of Environmental Protection (DEP), then you don’t have to install any of these devices.

For an official determination on if you must have a backflow device installed, consult a Professional Engineer, Registered Architect, or a Licensed Master Plumber. The following organizations will be able to refer you to a PE, RA, or LMP:


The following is an estimate of how much an installation should cost, depending on building size:

Very small (1 story)

$3,000 – $5,000

Small (2 stories)

$3,750 – $5,500

Small to mid-size (Car washes, laundromats, small manufacturers)

$5,000 – $7,000

Mid-size (Office complexes, large manufacturers, department stores)

$7,500 – $13,000

Large (High rises, hospitals)

$14,000 – $34,000

Maintenance and Inspection

These devices must be inspected every year, during the same month they were installed. Making sure they continue to be fully functional helps ensure the safety of those utilizing the building’s water.

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