As part of our water quality program, we maintain a database of backflow assemblies and ensure that they are in proper working order to prevent any cross-contamination of our water system. Now, what does this really mean? Well, for commercial or industrial buildings, buildings more than three stories tall, multi-family residences, and homes where there is more than one source of water can be found have to install a backflow assembly device, which prevents water from coming back into our distribution system. The rules the govern these devices and how we must maintain our records come from the Arizona Department of Environmental Quality. We even have rules listed in our Town Code Section 14. These devices stop water from flowing backwards into the system bringing with it potential contaminants and pollutants. A sample of the side of a home with a backflow assembly device is below.
Any of the homes that are connected to the separate purple-pipe irrigation system, or a well on their property, and are connected to our water system will have a backflow assembly installed. This second source of water needs to be prevented from entering our water distribution system, which is where the backflow device comes into play. Marana Water requires a reduced pressure assembly (RPA) because it provides the most protection. It works by maintaining a reduced pressure between two check valves that is lower than our system water pressure. If either of the valves are leaking, then the backflow is not working properly and needs to be repaired or replaced. The goal of these devices is to prevent back-pressure and back-siphonage into our water system. Back-pressure means there is more pressure in one system than is in the main distribution system. Back-siphonage happens when there is negative pressure in the distribution system like a main break of fire flow somewhere. You can think of it like how water drops back down into the glass when drinking through a straw. Both of these occurrences can pull polluted or contaminated water back into the potable drinking water system.
Just like other things in our lives, these devices require maintenance. Each assembly must show a passing test each year. It is our responsibility to track the passing tests and disconnect those that are not in compliance. It is the responsibility of the home owner/resident and the business owner to get the backflow assembly tested when it is due. Beginning August 1, a new round of testing will begin for our backflow customers. The chart to the right shows the schedule for those residential customers in the Gladden Farms and Rancho Marana neighborhoods that have testing requirements. While other residential customers might not be in these areas, they will still have a backflow assembly device that has a test requirement if it meets the above requirements. Those with assemblies will be getting reminder letters in the mail in the next few weeks and months stating when the test needs to be completed. The letter will also include a list of certified testers that are registered with the department who can complete the test on your behalf. Should the test not be done or not repaired after a failed test, the drinking water will be disconnected to the home or business.
Our backflow website has much more information on what a backflow assembly does, where it is located on the home, and more information on how to get it tested. You can find that page by clicking here. It is pretty incredible that something small can be so vital to the public safety of our water system.
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