Backflow testing in NYC is required by law for specific properties, such as those with multiple service lines or using certain industrial processes, and must be performed annually by a certified tester DEP.
At Gas Detectives, we take water safety seriously. Our backflow prevention services are designed to protect your building’s potable water supply from contamination while keeping you in full compliance.

Buildings with certain features or risks, such as multiple water service lines, roof tanks, or certain industrial uses.
New York State law requires certain properties and businesses to install, maintain and test backflow prevention devices, which stop contaminated water from flowing backwards into the main water supply.
Your drinking water is pushed from the city’s water main into your property’s plumbing by pressure and it should only flow in one direction. Sometimes, due to pressure changes in pipes, the water can flow backwards into city water lines and could contaminate the public water supply with human waste or chemicals.
To install a backflow prevention device, you must hire a Professional Engineer (PE) or Registered Architect (RA) to prepare a backflow prevention plan for your property. The PE or RA will send the plan(s) to DEP for approval. If the plans are approved, DEP will notify you via mail. You will then need to hire a Licensed Master Plumber (LMP) to install the backflow prevention device.
Backflow Prevention Devices
Your drinking water is pushed from the city’s water main into your property’s plumbing by pressure and it should only flow in one direction. Sometimes, due to pressure changes in pipes, the water can flow backwards into city water lines and could contaminate the public water supply with human waste or chemicals.
FAQs
Why are backflow prevention devices required?
Backflow prevention devices are an important component of our drinking water protection program and are legally mandated under the New York State Sanitary Code and the Rules of the City of New York for those businesses identified as posing a risk to the public water supply.
How can I be sure if my property requires a backflow prevention device?
To determine whether or not your property requires a backflow prevention device, hire a Licensed Professional Engineer (PE) or Licensed Registered Architect (RA).
How much will the installation of backflow prevention device cost?
The following prices are estimated based on average industry prices for parts and labor:
For large buildings (High rises, hospitals) installation should cost between $14,000 and $34,000.
For very small buildings (1 story) installation should cost between $3,000 and $5,000.
For small buildings (2 story) installation should cost between $3,750 and $5,500.
For small to mid-size buildings (car washes, laundromats, small manufacturers) installation should cost between $5,000 and $7,000.
For mid-size buildings (office complexes, large manufacturers or department stores) installation should cost between $7,500 and $13,000.
Will my property need more than one backflow prevention device?
If your property is required to have a backflow prevention device and has multiple water service lines, you must install a device on each line.
