Backflow Prevention –
What is it and Why Do We Need it?
Cross-connections in plumbing are defined as actual or potential connections between a potable and non-potable water supply. This can constitute a serious public health hazard. There are numerous well documented cases where cross-connections have been responsible for contamination of drinking water and have resulted in poisoning and or the spread of disease through the water.
This problem is a dynamic one because piping systems are continually being installed, repaired, replaced, or extended. Control of cross-connection is possible, but only through knowledge and vigilance. Under Public Law 99-339, the “Safe Drinking Water Act” (SDWA) was passed in 1986. This act placed the water purveyor with the primary responsibility for preventing water from unapproved sources, or any other substances, from entering the public water system.
All Municipalities with public water systems are required to have a cross-connection control program in place to protect the water supply. Backflow prevention devices are installed on water supply systems for this reason.
TYPES OF BACKFLOW DEVICES
There are many types of backflow devices, but there are only three types that can be tested:
1. Pressure Vacuum Breakers – PVB
These vacuum breakers are used where a condition of back-siphonage could occur. Back-siphonage can be the result of a total loss of pressure within the system due to a breakage in the main supply piping or other reasons. The pressure vacuum breaker is a mechanical device consisting of one spring loaded air inlet valve on the discharge side of the device. This device includes shut off valves and test ports on each end of the device. They are used in low or high hazard conditions.
2. Double Check Valve Assemblies – DCVA
The double check valve assembly is a mechanical device that consists of two spring loaded check valves. This device includes shut off valves and test ports on each end of the device. This device is effective against back pressure and is used to isolate low hazard pollutants (non-health threatening/non-toxic).
3. Reduced Pressure Zone Assemblies – RPZ
The reduced pressure zone assembly is a mechanical device that consists of two spring loaded check valves and a relief valve. This device includes shut off valves and test ports on each end of the device and can be used for backpressure, back-siphonage, and it can be used in toxic or high hazard conditions.
WHAT IS REQUIRED
A backflow prevention device needs to be inspected annually. The 2018 Uniform Plumbing Code in section 603.2 states:
Devices or assemblies installed in a potable water supply system for protection against backflow shall be maintained in good working condition by the person or persons having control of such devices or assemblies. Such devices or assemblies shall be tested at the time of installation, repair, or relocation and not less than on an annual schedule thereafter, or more often where required by the Authority Having Jurisdiction (AHJ). Where found to be defective or inoperative, the device or assembly shall be repaired or replaced. No device or assembly shall be removed from use or relocated without the approval of the AHJ. Testing shall be performed by a certified backflow assembly tester in accordance with ASSE Series 5000 or otherwise approved by the AHJ.
WHAT THE RESPONSIBLE PARTY SHOULD KNOW AND DO
1) Backflow devices are not limited to being installed on the main water line into the building from the water purveyor. You may also have them throughout the building on supply lines to equipment or machinery within the building. These are installed to protect the occupants within the building from a potentially hazardous condition. They should also be set up on an annual inspection plan.
2) If you are responsible for the safe operation of any backflow device you should partner with an experienced, licensed, certified, and insured backflow tester. Qualified testers are individuals who have passed an approved certification course and hold a valid license to test and repair or replace the devices. They may work alone as a sole proprietor or be employed by a larger company. Regardless, find someone who is knowledgeable on the various devices and knows what the local codes require in your area. They should be knowledgeable on how the device operates, how it should be properly installed, what the testing parameters are, and how to file all necessary documentation and/or permits that may be required for the work.
3) The testing procedure usually takes about 30 minutes. During this time the water will need to be shut down on the water line where the device is installed. Oftentimes this could be the entire building.
4) Backflow devices are well designed. Most all devices can be repaired. Replacement is not always necessary.