What is a Backflow Assembly Device?

Backflow is the flow of water or other mixtures (sometimes non-potable) into the potable drinking water distribution lines. This can be caused by a difference in pressure between private and public water lines. The pressure difference can cause water to go the wrong way up the pipe, creating the potential for water contamination to occur.

A backflow assembly device is one of many types of devices that prevents the backflow of water, or other substances, back into the drinking water system through a cross connection. A cross connection is any temporary or permanent connection between a potable drinking water system and any source or system containing non-potable water or any other substance. The device tracks the pressure and closes off flow when a loss of pressure is detected. This is how the device prevents backflow and prevents the risk of contamination, as long as the device is in good working order.

There are many types of cross connections that would require backflow assembly installation and annual testing. For residential customers these types of potential hazards are commonly underground irrigation systems, wells, a pool, or a boiler.

Protect Your Water Heater from Thermal Expansion

When your home has a backflow preventer installed, this could cause problems for your water heater unless a temperature and pressure relief valve (T & P valve) is installed. Without a T & P valve your water heater is susceptible to thermal expansion which could cause your water heater to explode. Contact a plumber to inspect the water heater to ensure a thermal expansion tank and a T & P valve are in place and are in good working order.

For more information and pictures of what these parts look like on a water heater see this Thermal Expansion Brochure made by the American Water Works Association.

What is thermal expansion and how does it relate to the installation of a backflow assembly?

Thermal expansion happens when water gets heated and expands, taking up more space. This can cause problems when extra pressure from the expanding water has nowhere to go, especially when a backflow prevention assembly is installed. Backflow prevention assemblies stop water from flowing backward into the public water supply, which creates a "closed plumbing system." In a closed system, the extra pressure can build up and cause leaks, burst pipes, or other damage.

An expansion tank is a small tank that absorbs the extra water when it expands, keeping the pressure from getting too high. To prevent damage, the Oregon Plumbing Specialty Code (OPSC) requires an expansion tank or another approved device to be installed when a closed plumbing system is created.  The tank is required only when the backflow assembly is installed on the domestic water service.   In most cases, thermal expansion tanks are not required for backflow assemblies installed for irrigation systems.

Diagram showing a water heater connected to a cold water supply with a backflow assembly, pressure gauge, and thermal expansion tank installed to control pressure in a closed plumbing system.

Testers can access SpryBackflow at  https://backflow.cityofsalem.net/

SpryBackflow Registration

• Testers will need to upload OHA certification and gauge calibration forms.
• With your account registration information and the customer pin, sign into SpryBackflow and complete the registration process. Afterwards, you will receive an email with a link to create a password once your registration has been approved by City staff. 
• Test reports must be entered electronically into SpryBackflow by registered testers. The City will no longer accept test reports via fax, email, or in person.
• To enter test reports, registered testers will need the pin(s) for each backflow assembly to be tested. The pin can be found on customer compliance letters. 
• Use the customer pin on SpryBackflow to see the location, make, model, and serial number of the backflow device(s) to be tested.
• Perform the test and fill out the details of the test on SpryBackflow. Some details will autofill. Once submitted, a report will be generated and will automatically be sent to the City. The Cross Connection Specialists at the City will validate the test report, and an automatic confirmation email will be sent to the tester and the customer (if customer information is on file).

• If you have any questions or need additional information, please email City of Salem’s Cross Connection Specialists at backflow@cityofsalem.net or call 503-361-2212.

Backflow Pin

• The pin can be found on the customer’s annual compliance letters from the City of Salem. The pin is highlighted in yellow.
• Each backflow assembly will have a unique pin and the numbers will change annually.
• Customer compliance letters will have the unique pin needed to enter the reports. Please plan to retrieve the pin from the customer directly.