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CBI understands the urgency of any backflow complication that may arise. Which is why we stock thousands of backflow devices and parts, most of which is traveling with your certified inspector when he arrives at your door.

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Backflow Learning Center


Chicago Backflow is focused on educating the community about what backflow is, what causes backflow, how backflow affects you, and the different types of backflow preventers.

Technical Definitions


Backflow
The reversed flow of a non-potable source into a potable system, because a pressure differential exists where the pressure on the non-potable side is greater than the pressure on the potable side.
Backflow Prevention Assembly (Backflow Preventer)
A mechanical device used to prevent the backward flow of contaminants or pollutants into a potable water distribution system.
Cross-Connection
Any arrangement of pipes, fittings, fixtures, or devices that directly or indirectly connects a non-potable water system to a potable water system.
Cross-Connection Control
The use of assemblies, devices, methods, and procedures to prevent contamination or pollution of a potable water supply through cross-connections.
Potable Water
Water that is safe for human consumption (meets the Safe Drinking Water Standards) and is aesthetically pleasing.

Frequently Asked Questions about Backflow Prevention


What is backflow?
Simply put: "Used" water is pulled back into the main water supply.
Technically: Water that has left the main water supply, then entered into your home or business to intermingle with numerous contaminents is no longer safe for drinking. Once this water is pulled back into the pipes in the wrong direction, it has the opportunity to mix with the clean drinking water, thus contaminating the entire town's water supply.
What causes backflow?
When there is a sudden drop in water pressure in your area (usually during the elimination of a fire, or concurrent use of large amounts of water by too many people at one time) the drop in pressure is what then pulls water that has already been expelled back into the main water supply.
How does backflow affect me?
Out of sight, all water pipes entering your home, the restaurant down the street, and your local hospital, are all connected to the same water supply. In your residence or business, any mechanically-controlled use of water (ie: lawn irrigation, fire sprinkler system, pop machines, pedicure bowls, etc.) a backflow preventer is a necessary accessory to your plumbing system. A "backflow preventer" is just what it sounds like. Once water pressure drops, the backflow preventer seals shut, not allowing any water to flow backwards in the wrong direction.
The EPA mandates that all backflow preventers be tested and certified once, sometimes twice per year, depending on the geographical location of the backflow preventer. If a water customer chooses not to meet this requirement, that customer will eventually be faced with the termination of their water service until they are able to show proof that their device has been properly tested and maintained. This annual or semi-annual testing is what ensures the safety of your drinking water.

Types of Backflow Preventers


Double Check Valve Assembly (DCVA)

double check valve assemblyThe Double Check Valve Assembly consists of two internally loaded, independently operating check valves together with tightly closing resilient seated shut-off valves upstream and downstream of the check valves. Additionally, there are resilient seated testcocks for testing of the assembly. The DC may be used to protect against a pollutant only. However, this assembly is suitable for protection against either backsiphonage or backpressure.

Seen on: Low hazard fire protection systems

Reduced Pressure Principle Assembly (RP)

reduced pressure principle assemblyThis assembly consists of two internally loaded independently operating check valves and a mechanically independent, hydraulically dependent relief valve located between the check valves. This relief valve is designed to maintain a zone of reduced pressure between the two check valves at all times. The RP also contains tightly closing, resilient seated shut-off valves upstream and downstream of the check valves along with resilient seated testcocks. This assembly is used for the protection of the potable water supply from either pollutants or contaminants and may be used to protect against either backsiphonage or backpressure.

Seen on: High hazard systems such as lawn irrigation, boiler makeup, chiller makeup, and domestic water

Pressure Vacuum Breaker (PVB)

double check valve assemblyThe PVB includes a check valve which is designed to close with the aid of a spring when flow stops. It also has an air inlet valve which is designed to open when the internal pressure is one psi above atmospheric pressure so that no non-potable liquid may be siphoned back into the potable water system. Being spring loaded it does not rely upon gravity as does the atmospheric vacuum breaker. This assembly includes resilient seated shut-off valves and testcocks. The PVB must be installed at least twelve (12) inches above all downstream piping and outlets. The PVB may be used to protect against a pollutant or contaminant, however, it may only be used to protect against backsiphonage. It is not acceptable protection against backpressure.

Seen on: lawn irrigation systems having intermittent use

Now that you have been properly educated about the practice of backflow prevention, you should have a better idea of just how important this inspection and service is to not only yourself, but your entire community. It is important that the backflow testing companies and individuals that represent them maintain the standards set by the EPA, and do not ever try to cut corners on such an important service. It is crucial that you, as a water customer, choose a backflow prevention company that you feel is qualified to perform your backflow test. The health and well being of not only yourself, but your community as well, is depending on you.