When we look at the required cross-connection protection, it is important to understand the system type, piping material, water supply to the system, and other crucial factors. In the United States, we have two hazard levels: low and high. The fourth edition of IAPMO’s Backflow Prevention Reference Manual defines low hazard as, “The possible or potential impairment of the quality of the potable water to a degree that does not create a hazard to the public health, but which does adversely and unreasonably affect the aesthetic qualities of such potable water for domestic use.” The manual defines high hazard as, “Any actual or potential threat of contamination to the potable water supply is considered a health hazard. Such materials entering the water supply are considered toxic or a contaminant.” Simply put, a high hazard can make you sick; a low hazard will not.
When we’re discussing the required protection on fire protection systems in backflow training classes, students frequently ask the following: Why are most water-based fire protection systems considered to be low hazard? How is water that is contained in what we would consider a gigantic dead leg, in most cases in black iron pipe that is not rated for potable water, still considered a low hazard? Do we really think that if we drank a glass of water from a 30-year-old fire sprinkler system it would not affect our health? Those are reasonable questions.
The industry and code and standard bodies came to that conclusion many years ago. As we gained a better understanding of the need for testable backflow assemblies on fire systems, the fire protection industry was concerned about the pressure and volume loss that would occur as a result of this protection being installed. They worried about check valves failing to open and the effect of a differential relief valve opening when the fire system was activated. The cross-connection and fire protection industries came to a consensus that as long as no chemical additives were added to a water-based system, it would be considered low hazard. There are exceptions to this rule, which we will discuss later in this article.
The 2024 Uniform Plumbing Code (UPC®) only addresses fire protection systems to the point of connection to the domestic water supply. In Section 603.5.14, Protection From Fire Systems, it states:
Except as provided in Section 603.5.14.1 and Section 603.5.14.2, potable water supplies to fire protection systems that are normally under pressure, including but not limited to standpipes and automatic sprinkler systems, except in one or two-family or townhouse residential sprinkler systems, piped in materials approved for potable water distribution systems shall be protected from backpressure and back siphonage by one of the following testable devices:
1) Double check valve backflow prevention assembly (DCVA)
2) Double check detector fire protection backflow prevention assembly (DCDA)
3) Reduced pressure principle backflow prevention assembly (RP)
4) Reduced pressure detector fire protection backflow prevention assembly (RPDA)
As you can see, the code allows for either double check or reduced pressure assemblies, or detector assemblies of both types, for water-based systems. In systems that contain chemicals, the degree of hazard is increased. In Section 603.5.14.2, Chemicals, it states:
Where antifreeze, corrosion inhibitors, or other chemicals are added to a fire protection system supplied from a potable water supply, the potable water system shall be protected by one of the following:
1) Reduced pressure principle backflow prevention assembly (RP)
2) Reduced pressure detector fire protection backflow prevention assembly (RPDA)
It is important to understand that this section does not look at the toxicity of the additives. Any additive will change the hazard level from low to high. It also does not mention volume of additives — any change to the water, no matter how small is, will require a high hazard assembly. Even if an antifreeze loop (see figure 1) only feeds 1% of the system, the entire system is now high hazard. If the antifreeze loop itself is protected by a reduced pressure assembly (see figure 2), the containment protection on the entire fire protection system shall also be an RP or a RPDA.
What if a fire department connection is part of the fire protection system? The code states in Section 603.5.14.1, Fire Department Connection:
Where fire protection systems supplied from a potable water system include a fire department connection that is located less than 1,700 feet (518.2 m) from a nonpotable water source that is capable of being used by the fire department as a secondary water supply, the potable water supply shall be protected by one of the following:
1) Reduced pressure principle backflow prevention assembly (RP)
2) Reduced pressure detector fire protection backflow prevention assembly (RPDA)
The code also points out the following:
Non-potable water sources include fire department vehicles carrying water of questionable quality or water that is treated with antifreeze, corrosion inhibitors, or extinguishing agents.
All these questions need to be addressed when deciding on the proper protection. The installation of the fire department connection does not require the installation of high hazard unless any of the conditions above are a factor. In many situations, a DCVA or DCDA is acceptable protection for water-based systems with fire department connections.
What about standpipe systems? Dry standpipes are physically air-gapped from the water supply and, as such, require no protection. In a fire situation, the fire department connects to the system from a fire engine and a fire hydrant to pressurize the standpipe (see figure 3). Wet standpipe systems are considered a low hazard and must be protected with a double check valve assembly (see figure 4).
Residential fire protection systems may also require backflow protection, depending on the system type. If it is a multipurpose system using potable water piping that also supplies the plumbing fixtures, then it would require no protection. If it is a stand-alone system containing no chemicals, it would be low hazard and require a double check valve assembly. If chemicals or additives are added to the system, a high hazard reduced pressure principle would be required.
We should look at any water system connection as a unique installation. When we test any backflow prevention assembly, we should be conducting a crossconnection survey of the installation to ensure the correct valve has been installed. Being proactive is the only way to ensure system safety and protect public health.
