Throughout my 45 years in the plumbing industry, I have seen about every type of plumbing installation. I have worked in residential, commercial, industrial, and institutional settings, and the inventiveness of plumbing installations never ceases to amaze me.
Approved backflow prevention devices and assemblies go through many tests and must meet extensive ASSE standards to be accepted across North America. It is rare for a backflow preventer to fail due to mechanical issues within its early years of installation, but it does happen. What is more common is that they were not installed correctly from the start or during replacement. In some cases, they are even removed by individuals who do not understand the importance of cross-connection control.
When a backflow preventer is initially installed, they are normally inspected by the water authority or plumbing inspector. The bigger issues arise when a replacement is required or the facility has changed function, such as a strip mall that has repurposed a retail store and moved a hair and nail salon into that space. The retail store has a low-risk classification, meaning there is little or no chance of polluting or contaminating the potable water system. On the other hand, the salon uses dangerous chemicals daily and has a much greater risk of contaminating the water.
Most trained backflow testers are aware of the codes in their local jurisdiction. During the tester certification class, they become familiar with the criteria of proper installation. They know it is their responsibility to be the “eyes” of the water purveyor and make note of possible incorrect installations.
Thankfully, some of the photos we are about to see were forwarded to us by these testers and surveyors and we can see just how inventive some folks are.
We can start with the good. There is no shortage of “good” installation photos to share, whether it be a reduced pressure principal backflow prevention assembly or a spill-resistant vacuum breaker assembly. Different assemblies and devices have specific uses and functions. The choice of the correct backflow prevention is determined by the degree of hazard, the type of backflow that might occur, the location and the system characteristics. We mentioned the degrees of hazard are high risk (health hazard) or low risk (nonhealth hazard).
There are two types of backflow that we are concerned with, backpressure and backsiphonage. Some backflow preventers, if subjected to backpressure, will not function properly. It is particularly important to identify the type or types of backflow that may occur and choose the correct device or assembly.
Some assemblies and devices have installation criteria that must be met. For example, an atmospheric vacuum breaker cannot be subjected to backpressure and must be installed 6 inches above the flood level rim of the fixture served and all downstream piping. It cannot be kept under continuous pressure, which is defined as being under pressure for more than 12 hours in a 24-hour period. Depending on which of the model or state plumbing codes you are using, definitions may be slightly different.
Right: Example of backflow preventer installed below grade.
A double check valve assembly or reduced pressure principle assembly installed as containment or isolation protection must be “accessible” for testing and maintenance. Would you consider the assembly that appears in the photo above to be accessible? Some authorities consider this to be accessible. With a ladder or lift you can test this assembly. Other areas have a much more defined meaning of accessible, with a minimum of 12 inches above the surrounding area and no higher than 60 inches above the floor.
Speaking of elevation issues, let us discuss backflow preventers in pits or vaults. There are very few backflow preventers that are allowed to be installed below grade. A good rule of thumb is if the backflow preventer must open to atmosphere to function properly, it cannot be installed below grade. When the air inlet or pressure differential relief vent opens during a backflow condition and the backflow preventer is below grade, there is a possibility that the pit or vault may be filled with contaminated or polluted substances. These substances can now enter the potable water system.
Installation criteria includes ensuring the assembly is in the proper orientation. Double check and reduced pressure backflow prevention assemblies may be installed in any orientation for which they have been approved by the listing agency. This may include vertical up or vertical down flow orientations. The assemblies may also be installed horizontally, or in a N or E pattern orientation. Vacuum breaker devices and assemblies must be installed in an upright position. Sometimes while testing a backflow assembly, the tester is not certain if the orientation is acceptable. There is a great reference source for this information: www.asse-plumbing.org. If you go to this website and look at “Certified Product Search” you can look up every backflow preventer by either the ASSE standard number, manufacturer, or the model number. This will list the approved orientation along with acceptable shut-off valves allowed to be used with the backflow preventer.
Middle: Incorrect orientation for this reduced pressure backflow prevention assembly.
Right: Atmospheric vacuum breaker in place of a 90-degree elbow.
I mention the shut-off valves for a reason. According to both ASSE and USC Listings and Standards, an approved assembly must be installed the way it was received from the manufacturer. This means without alterations, additions, deletions, or relocation of any component of the assembly. Changing or rearranging the components will void the listing approval. Manufacturers have begun certifying their assemblies with more than one specific shut-off valve type. If a valve needs to be replaced you can check the assembly’s product listing to see which specific shut-off valves are approved for that model. These valves are listed on the ASSE product listing website.
Now to the not so pretty. The photo on the previous page shows a backflow preventer 25 feet or more above the floor. The Uniform and National Standard Plumbing codes require a permanent platform to be installed at each assembly installed over 60 inches above the finished floor. The International Plumbing Code simply states that the assembly must be a minimum of 12 inches above the floor and accessible. That leaves approval up to the installer or inspector if they consider the assembly accessible. The valve in the photo is in that type of jurisdiction and indeed was considered a proper installation by the local code official. Other installations we see in the field, such as double check valve assemblies in pits or vaults, are code approved in many areas but that does not make it easy on the tester when we install assemblies in confined spaces.
We also see inappropriate uses of backflow preventers. As you can see in the photo above, some brilliant mechanic used this atmospheric vacuum breaker in place of a 90-degree elbow. This installation is wrong on so many levels. It is under continuous pressure, it is installed in the wrong orientation, and it is unnecessary; protection is not required.
Then we have the people who just want to make life easy on themselves. On the following page is a photo of a water feed for a floor mount urinal, and more than likely several of them. The method of backflow protection required by code and by the product standard on most urnials is an atmospheric vacuum breaker to prevent backsiphonage. Installed with a flushometer valve it is the preferred method of protection. Physical air gaps are the most effective means of backflow protection. It is a method that requires a clean break between the potable water supply and the vessel to which the water is entering. The clear space must be a minimum of twice the inside diameter or effective opening to prevent backflow from occurring.
Right: Homeowner’s solution for achieving the correct elevation for pvb.
Lastly, I would like to discuss people who for some reason find it hard to follow the rules, even if by following the rules they could do the installation correctly and at a lower cost. The chemicals used to treat our lawns are very toxic, a high hazard situation. Irrigation systems are always a high hazard installation. When lawn irrigation systems are installed, they need to be protected by a high hazard device or assembly. The most common assembly on these systems, which do not include any chemical injection, is a pressure vacuum breaker assembly (PVB). Since they are a type of vacuum breaker, the PVB is not allowed to be subjected to any type of backpressure. It must be mounted at lease 12 inches above all downstream piping and the surrounding area. In this photo, this homeowner irrigated their garden on the hillside. This was their solution for achieving the correct elevation. A better suggestion would be to install a reduced pressure principle assembly as the required protection. That would allow the protection to be installed at an elevation below the piping. The reduced pressure principle assembly protects against high hazard backpressure and backsiphonage. I would have to assume the higher cost of the assembly was a more cost-effective and aesthetic way to go.
There are many different thoughts on the proper way to protect our potable water supply. When in doubt please turn to your local authority having jurisdiction for what is accepted and required in your area. If you would like to learn more, please enroll in an approved ASSE school to take the certified tester course or a surveyor class for a more in-depth look at recognizing hazards and proper protection. If there are no ASSE-approved providers in your area, IAPMOBPI would be happy to discuss conducting a class in your area. Please contact them for more information.
You use the term ” degrees of hazard are high risk (health hazard) or low risk (non-health hazard).” This tern degree of hazard is overused and not appropriate for controlling cross-connection. There is no non-health hazard situation. There is always a risk. You can’t make a health hazard into a non-health hazard. I hope the plumbing and cross-connection industries will use the correct terminology. Drinking water from a plumbing system is a risk, as you mentioned. You can change the risk but not the hazard. The potable plumbing system is a hazard. What is the risk of consuming the water from that system? If the potable water plumbing system complies with the plumbing codes, the risk of consuming water is low. If the potable water plumbing system is not in compliance with the plumbing codes, the risk of consuming compromised water is high. “The salon uses dangerous chemicals daily and has a much greater water contamination risk.” It is not necessarily true if the potable water system complies with the plumbing code.
You failed to mention the most prominent problem with installing RPs, which is failing to consider the possibility of a catastrophic discharge. The manufacturer’s specifications, regulations, and codes require installing a drain capable of handling a catastrophic discharge. Alarms or shut-off devices are required if the discharge cannot be obtained.