Cross Connection Program

A Cross Connection is defined as any actual or potential physical connection between a public water system, or the customer’s water system, and a source of non-potable liquid, solid or gas that could contaminate the public water system by backflow.

Cross Connection Control protects public health by requiring the installation of backflow prevention assemblies at all actual or potential cross connections. These assemblies must be registered with the District and tested annually by a certified backflow assembly tester (BAT) per WAC 246-290-490

Cross connections can exist in all plumbing systems; therefore the District operates and maintains a Cross Connection Control Program. This program helps reduce the risk of contaminates entering into the public water supply by monitoring cross connections and backflow protection.

Frequently Asked Questions

What is a cross connection?

A cross connection is any physical arrangement or potential arrangement whereby the District’s water system is or may be connected, directly or indirectly, with any other water supply system, sewer, drain, conduit, pool, storage reservoir, plumbing fixture, or other device which contains, or may contain, contaminated water, sewage, or other waste or liquid of unknown quality which may be capable of having the potential to contaminate the District’s water supply as the result of backflow or backsiphonage. By-pass arrangements, jumper connections, removable sections, swivel or changeable devices, and other temporary or permanent devices through which, or because of which, a backflow or backsiphonage may occur, are considered to be cross-connections.

What is a backflow prevention assembly?

A backflow prevention assembly is a certified assembly that prevents the undesirable reversal of flow of water or other substances through a cross-connection into the District’s water system, or consumer’s potable water system.

Why am I required to test my backflow prevention assembly annually?

The Safe Drinking Water Act Amendments of 1986, and regulations of most states, state that the water purveyor has the primary responsibility of preventing water from unapproved sources, or any other substances, from entering the public potable water system. The health agency has the overall responsibility for preventing water from unapproved sources to enter either the potable water system within the water consumer’s premises or the public water supply directly. North Perry Avenue Water District operates and maintains a cross connection control program, in accordance with the Department of Health requirements per Washington Administrative Code (WAC) 246-290-490 which states, “Purveyors have the responsibility to protect the public water systems from contamination due to cross connection. Cross connections which can be eliminated shall be eliminated. The Purveyors shall work cooperatively with the local authorities to eliminate or control potential cross connections.” In accordance with WAC 246-290-490, North Perry Avenue Water District requires all backflow prevention assemblies will be tested upon installation, repair, or relocation and annually by a certified Backflow Assembly Tester (BAT). All tests are due to the District on or before the due date printed on your annual test reminder letter to avoid fines and potential termination of service.

What does the District's premise isolation policy mean in regards to backflow prevention assembly placement?

The District’s responsibility for backflow prevention will begin at the water supply source and include all water treatment, storage, and distribution facilities. The District’s responsibility ends at the point of delivery to the consumer’s water system, which begins at the downstream end of the District’s service connection water meter located on the public right-of-way or utility-held easement. Under provisions in WAC 246-290-490, the District is not responsible for eliminating or controlling cross-connections within the consumer’s water system (plumbing). That responsibility falls under the jurisdiction of the local administrative authority that is authorized to administer and enforce the Uniform Plumbing Code.

I have my assembly tested every year, but my neighbor says they have never heard of the testing requirements. Why is that?

There may be several reasons why your neighbor has not received any notifications from North Perry Water, the most likely being that we don’t know about the installation. Many times customers make modifications to their private water system and do not inform the district. Have them give us a call (360) 373-9508, so we can check their account and go over the situation with them.

I am not using my irrigation system anymore. Do I still need to test the backflow assembly?
As long as the irrigation system is physically connected to the water system, the assembly must be tested. North Perry Water can suspend the testing requirement if the customer provides a physical disconnect between the irrigation system and the public water system by removing the assembly and/or cutting and capping the water supply line. This must be inspected by North Perry Water staff. Please contact the office at (360) 373-9508 with additional questions or to schedule an inspection.

Backflow Prevention Requirements

Washington State law requires all public water systems maintain an active Cross Connection Control Program to protect public health.
The State of Washington Department of Health (WSDOH) and North Perry Avenue Water District (NPW) have implemented the following pertaining to backflow , WAC 246-290-490 and NPW Resolutions 590 and 650 (including all subsequent and existing NPW resolutions and amendments) , that ensure our residents receive safe drinking water.
NPW has adopted premise isolation, requiring that installation of backflow assemblies be located at the water meter, directly downstream. Testing of assemblies is required at time of installation, after removal or repairs and annually.


  • For new installations: A Reduced Pressure Backflow Assembly (RPBA) is the minimum level of protection allowed for premise isolation.
  • For existing installations:
    • Anytime a business applies for a building improvement permit, changes use or ownership, the building owner will be required to install an RPBA at the water meter as Premises Isolation.
    • When a previously installed, non-premise assembly or premise assembly of lesser hazard protection (i.e.: DCVA vs RPBA) fails testing and cannot be repaired “In Place”, the assembly is required to be moved and/or upgraded, or both, to current hazard protection practices and installed at the water meter as Premises Isolation.


  • Double Check Valve Assembly (DCVA) is the minimum level of protection allowed for premise isolation (e.g.: irrigation, booster pumps, fire suppression, etc.).
  • RPBA is required, and is the minimum level of protection, for any residence with an Auxiliary water source on premises.
  • RPBA may be required if qualifying hazard exists, as determined by NPW.
  • When a previously installed, non-premise assembly fails testing, and cannot be repaired “In Place”, the assembly is required to be moved and installed at the water meter as Premises Isolation.
  • Anytime a residence, with previously installed non-premise backflow protection changes ownership, the property owner will be required to install Premise Isolation at the water meter.

1: Commerical includes (not limited to): Industrial, Municipal, Businesses, Churches, Organizations, Schools, Apartment buildings/complexes.
2:Residential: single family houses and duplexes housing single family per side.

Testing Dates for Backflow Prevention Assemblies

Customers with irrigation systems or other actual or potential cross-connections are required by state law, according to WAC 246-290-490, to have their backflow prevention assemblies tested on an annual basis. District customers with backflow prevention assemblies can have their tested completed and reports submitted to the District by the tester, using our backflow test submission portal at any time prior and up to the printed due date on your assembly test reminder letter. Reports submitted after the annual due deadline will be subject to fines and/or disconnection.

Certified Backflow Assembly Tester List

Washington Certification Services Backflow Assembly Tester List
The Department of Health Office of Drinking Water has authorized Washington Certification Services at Green River College to maintain a list of certified Backflow Assembly Testers.

North Perry Avenue Water District does not maintain this list, nor claim responsibility for the quality of work or any other aspect of the testers listed.

Web Test Entry

Testers are now required to enter their test reports on our web test portal.
Test results may be entered in the field using a tablet with a WiFi connection or a smartphone. You may also continue using paper in the field and submit them online when you are back in the office.

The website will track your submitted tests; you will no longer have to contact the utility to find out if your tests have been received.

A New Way to Submit Tests

  1. Test the backflow assembly.
  2. Log into our Web Portal
  3. Enter the hazard Serial number or Address to locate the tested backflow assembly (If multiple assemblies at one site choose the correct serial # for your test submittal).
  4. Select “Test Equipment” used and input test results following the guided step process.
  5. When finished entering test data check the box stating: “I hereby certify that the above data is correct and that the backflow prevention device is in proper working condition.
    Your Test Result is a Legal Document and submission constitutes your Digital Signature.
  6. Click the “Submit Results” button.

For more information regarding cross connection please contact the District’s Cross Connection Team at 360-373-9508 x 211.