What Is A Backflow Preventer?

Backflow preventers are  used in cross connections in irrigation systems. A cross connection is a point in a plumbing system where the drinking water supply is connected, or can be connected, to a non-drinking water source.

A one-way valve is integrated into the plumbing to keep contaminated water from entering your drinking water or the city's water supply.

The one-way check valve assemblies allow the water to only move forward into the system, not backwards into the water supply pipes that supply fresh water to homes and businesses. This is how backflow assemblies protect our water supply.

Annual testing of your irrigation backflow system is required by Washington State Code WAC 246-290-490 to assure that it is in perfect working order.

The yearly test will identify any problems so they can be corrected. Plantscapes Inc. offers both backflow preventer installation and annual testing, performed by certified backflow assembly testers. Upon completion of the test, we will provide you with all the necessary paperwork required by your local utility.

Call Plantscapes at 206.623.7100 to schedule a certified backflow test.

Requirements & Types of Devices

Washington State requires that any cross connection - such as an irrigation system - have a backflow preventer. The backflow preventer may be required to be located on the water service line, within the building, or both locations. After an initial inspection and testing of a newly installed backflow preventer, the water customer is required to have the backflow preventer tested on an annual basis.

Irrigation systems are considered low hazard installations

The most commonly used irrigation system backflow preventers are:

Double check valve assemblies (DCVA)
Pressure vacuum breaker assemblies (PVB)
Atmospheric vacuum breakers (AVB)

Plantscapes' technicians will ensure that only an approved device will be used with your irrigation system.


Inspection of Backflow Preventers
Seattle Public Utilities inspects backflow assemblies upon installation and conducts periodic re-inspections on all existing assemblies. New assemblies must be tested by a State of Washington certified backflow assembly tester prior to putting into service. A copy of the test report must be provided to Seattle Public Utilities.

Annual Testing of Backflow Preventers Is Required
All backflow preventers must be tested annually by a State of Washington certified backflow assembly tester and after repair or replacement. A copy of the test report must be provided to Seattle Public Utilities. Plantscapes backflow assembly testers are certified and will provide you with all the necessary paperwork required by your municipality.

If you have any questions, please give Plantscapes a call. We'll gladly explain what is required by your local utility and we'll schedule an appointment for a backflow test.

In Seattle, you can call Plantscapes at 206.623.7100 to schedule a backflow test. Plantscapes' main office is open 8:00 AM to 5:00 PM, Monday to Friday.


Each address within the City of Issaquah that contains a backflow device is assigned an account number
A yearly due date for inspection of that device is assigned. Reminder letters are mailed for the devices that are due to be tested, along with detailed account information.

If an annual test is not performed, the city terminates the water service at that particular address. Water service will only be restored when the backflow devices are in compliance with Washington State codes.

If your backflow system fails the test, repairs must be performed immediately. A backflow assembly that has failed will not protect our water supply. Plantscapes Inc. will be able to assist you with this issue. Your account cannot be considered current unless or until each backflow assembly has passed the tests.

Once the test is completed successfully, Plantscapes will provide you will the the paperwork you need to file with your municipality to certify that the backflow system is operating correctly.

On the Eastside, you can call Plantscapes at 425.392.0905 to schedule a backflow test.


Even the best backflow assembly can fail because of freezing, debris, improper installation and unapproved plumbing connections. That’s why state law requires that backflow assemblies be tested annually by a certified backflow assembly tester—to ensure that the assemblies will function if there is a backflow event.

Cross Connection Control Program
Through the city's Cross Connection Control Program, the Utilities Department maintains a database of assemblies installed throughout the city, monitors their testing and sends customers a reminder notice, an assembly report and an updated list of qualified testers when testing is due. Your efforts in performing required testing and reporting new cross connections when found or created goes a long way in helping protect your drinking water quality.

To schedule a backflow test in Bellevue, please call Plantscapes Inc. at 206.623.7100

Request a Backflow Test

If you'd like to speak with a Plantscapes' representative to schedule an Irrigation Backflow test, just fill out the form below and we'll contact you within one business day.

Our calendar fills up quickly, so we may not be able to schedule your visit at the time or date you request, but we'll do our best to accommodate you.

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Schedule an Appointment
If you'd like to set up an Irrigation Backflow Test, fill out the form and we'll get back to you by the next business day.