Frequently Asked Questions

Cross Connections
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What is a cross connection?
Where are cross connections found?
What causes a cross connection?
How often must I have my backflow assembly tested?
Who can test my backflow assembly?

What is a cross connection?
A cross connection is a point in the plumbing system where the potable water supply is connected directly or can be connected directly to a non-potable source.
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Where are cross connections found?
A cross connection exists wherever the potable water supply is connected to a plumbing fixture. However, most new fixtures have built-in protections to avoid a cross connection. Commonly found cross connections can occur in hose bibbs, irrigation sprinkler systems, boilers, swimming pools, fire sprinkler systems and auxiliary water supplies.
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What causes a cross connection?
A cross connection may occur due to backflow caused by unprotected fixtures that are subjected to backsiphonage or backpressure. Backsiphonage is caused by a negative or reduced pressure in the supply line to a facility or plumbing fixture. Backpressure may cause backflow to occur whenever a potable water system is connected to another system at a higher pressure.
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How often must I have my backflow assembly tested?
All backflow assemblies must be tested upon installation, after any repairs, if moved to a new location, and annually thereafter.
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Who can test my backflow assembly?
Testing can only be performed by a Washington State Department of Health certified backflow tester. A copy of the test report must be sent to the District and a copy should be maintained in your personal files.
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