FAQs

Backflow Prevention Frequently Asked Questions

• Additional questions?

  For questions not answered above regarding backflow, please contact the City of Hermiston Water Department at 541-567-5521.

• Can the Certified Tester repair or replace my device if it fails?

  No, if they are not also a licensed plumber. The State requires that a licensed plumber (or the owner) do the repair or replacement. Many licensed plumbers are also certified to perform the test. If your device fails the test, once it's repaired or replaced it must be tested to ensure it is working properly.  

• How often does my device need to be tested?

  Backflow assemblies must be tested at the time of installation, annually after installation, after repairs and after relocating.

• Is backflow prevention required?

  Yes, where a cross-connection and/or backflow can occur. The State of Oregon requires backflow prevention devices to be installed, then tested annually to protect the health & safety of the public water system. In order to meet state law, the City is required to moniter testing of the devices

• What is a backflow preventer or device?

  A backflow preventer is a means or mechanism to prevent backflow, basically keeping water from flowing backwards into the public water main. The basic means of preventing backflow is an air gap, which either eliminates a cross-connection or provides a barrier to backflow. The basic mechanism for preventing backflow is a mechanical backflow preventer, which provides a physical barrier to backflow. The principal types of mechanical backflow preventer are the reduced-pressure principle assembly, the pressure vacuum breaker assembly, and the double check valve assembly. A secondary type of mechanical backflow preventer is the residential dual check valve.

• What is a cross-connection?

  A cross-connection is any temporary or permanent connection between a public water system or consumer's potable (i.e., drinking) water system and any source or system containing nonpotable water or other substances that are not safe to drink or may impact the taste or odor of water. Common cross connections include hot tubs, pools, sprinkler & irrigation systems & auxiliary water systems (wells).

• What is an air gap?

  An air gap is a vertical, physical separation between the end of a water supply outlet and the flood-level rim of a receiving vessel. This separation must be at least twice the diameter of the water supply outlet and never less than one inch. An air gap is considered the maximum protection available against backpressure ro backsiphonage but is not always practical and can easily be bypassed.

• What is backflow?

  Backflow is the undesirabble reversal of flow of nonpotable water or other substances through a cross-connection and into the piping of a public water system or consumer's potable water system. There are two types of backflow... backpressure backflow and backsiphonage. 

• What is backpressure backflow?

  Backpressure backflow is backflow caused by a downstream pressure that is greater than the upstream or supply pressure in a public water system or consumer's potable water system. Backpressure (i.e., downstream pressure that is greater then the potable water supply pressure) can result from an increase in downstream pressure, a reduction in the potable water supply pressure, or a combination of both. Increases in downstream pressure can be created by pumps, temperature increases in boilers, etc. Reductions in potable water supply pressure occur whenever the amount of water being used exceeds the amount of water being supplied, such as during water line flushing, fire fighting, or breaks in water mains

• What is backsiphonage?

  Backsiphonage is backflow caused by a negative pressure (i.e., a vacuum ~ or partial vacuum) in a Public water system or consumer's potable water system. The effect is similar to drinking water through a straw. Backsiphonage can occur when there is a stoppage of water supply due to nearby fire fighting, a break in a water main, etc.

• Who can test my backflow device?

  An Oregon State Certified tester can test your device.

• Why do water suppliers need to control cross-connections and protect their public water systems against backflow?

  Backflow into a public water system can pollute or contaminate the water in that system (i.e., backflow into a public water system can make the water in that system unusable or unsafe to drink), and each water supplier has a responsibility to provide water that is usable and safe to drink under all foreseeable circumstances. Furthermore, consumers generally have absolute faith that water delivered to them through a public water system is always safe to drink. For these reasons, each water supplier must take reasonable precautions to protect its public water system against backflow.