Dual Check Valve (DuC) Backflow Device

Dual Check Valve (DuC) Backflow Device

On May 5, 2014 the state regulations (Florida Administrative Code (FAC) Chapter 62) related to protecting the public water supply were changed significantly. 

Every drinking water system in Florida must have a cross connection control program, more commonly known as a backflow prevention program. (See Section 62-555.360 Cross Connection Control for Public Water Systems)

Pursuant to Chapter 50.40 Cross Connection Control Program Code of Ordinances City of Pembroke Pines The minimum backflow protection to be provided and the different categories of facilities that require backflow preventers, as required by the city, are listed in Table 62-555.360-2 of the Florida Administrative Code. Residential Service Connection - DuC Minimum (owned and installed by city personnel when setting the meter) (refurbished or replaced every ten years by city.” 


  • With the State’s guidelines for backflow prevention and the City’s implemented Cross-Connection Control Program (CCCP) a Dual Check Valve (DuC) backflow device is required at your residence. 
  • When a backflow prevention device is installed, a “closed” plumbing system is created. This means that any increase in pressure caused by the expansion of heated water may have nowhere to escape.
  • This buildup of pressure may lead to serious consequences such as a ruptured or distorted hot water tank or a collapsed flue within the gas-heated water tank that may lead to the release of toxic gases, such as carbon monoxide.
  • The Florida Building Code requires all plumbing systems that are classified as “closed” systems have a device installed for controlling pressure.
  • As a result, each resident should have an assessment done by a licensed plumber to determine if an expansion tank or a combination ball valve and relief valve is required on their system.

For more information on Expansion Tank:


 (Information courtesy of Bradford White)


For more information on Combination Ball Valve and Relief Valve:


  (Information Courtesy of WATTS.) 

Informational purposes only (not a product endorsement)


Frequently Asked Questions (FAQ)


What Is a Dual Check Valve Device (DuC)?

The Dual Check Valve backflow preventer device is a mechanical device designed to prevent backflow into the residential water system, it consists of two independently acting, spring-loaded check valves and is effective against backpressure and back-siphonage.  The device is only approved for residential service connections. 

What is The Function of a DuC?

In a backpressure condition, the increase in pressure will force the checks to close tighter. If the second check is not working, the first check can act as a backup to stop the backpressure from going through the device.

How will I be notified if a DuC will be installed on my property?

Look for information packet to be hung on your front door handle, followed by a blue door hanger, prior to installation. 

How Is It Installed?

The DuC will be installed in your water meter box by the city or its contractor.


What Is Back-Siphonage and Back Pressure?