Drinking Water

Cross Connection Control

In compliance with Washington State Administrative Code 246-290-490, which regulates the city’s Cross Connection Control Program, we may be inspecting the drinking water system at your property to ensure it is protected from contamination. We do this by using backflow prevention assemblies. These assemblies vary in size, shape, value and location; however, they all do the same thing--they prevent dangerous backflow conditions.

Our goal is to protect your drinking water and the city’s drinking water distribution system.

What is Backflow?
It's just what it sounds like; the water is flowing in the opposite direction from its normal flow. With the direction of flow reversed due to a change in pressure, backflow can allow contaminants to enter your drinking water system through cross connections.

What is a Cross Connection?
A cross connection is a permanent or temporary piping arrangement which can allow your drinking water to be contaminated if a backflow condition occurs. For example, if a garden hose is left in a bucket of soapy water and there is a change in water pressure, the soapy water could flow back into your drinking water system.

Where are Cross Connections found?
Whenever a plumbing fixture is connected to the drinking water supply, a potential cross connection exists. Most of the time these cross connections are controlled by the use of a backflow prevention device. These devices are usually installed by a plumber when the building is constructed and many of them need to be tested and maintained annually.

What causes water to flow backwards?
Backsiphonage is the reversal of normal flow in a system caused by a vacuum or partial vacuum within the water supply piping. Backpressure is the reversal of normal flow in a system due to pressure higher than the supply pressure.

Why do I have to test my Backflow Assembly annually?
If you have an irrigation system for your yard, boiler, pool/spa, water feature, fire sprinkler system or photo development equipment, state law requires that you get a backflow prevention assembly to prevent contaminated water from flowing back into your drinking water--a serious health hazard. Many businesses are also required to have backflow prevention.

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.

What is Premise Isolation?
Premise Isolation is backflow prevention installed or created at the incoming source to the property (usually at the meter) with an air gap and/or Reduce Pressure Backflow Assembly (RPBA). This will be required for service connections posing a high health cross connection hazard including, but not limited to, the following:

  • Agricultural (farms & dairies
  • Beverage bottling plants
  • Car washes
  • Chemical plants
  • Commercial laundries, dry cleaners
  • Premises where both reclaimed water and drinking water are provided
  • Film processing plants
  • Food processing facilities
  • Hospitals, medical centers, nursing homes, veterinary, medical and dental clinics, and blood plasma centers
  • Laboratories
  • Metal plating
  • Mortuaries
  • Petroleum processing or storage plants
  • Piers and docks
  • Radioactive material
  • processing plants or nuclear reactors
  • Radioactive material processing plants or nuclear reactors
  • Survey access denied or restricted
  • Wastewater lift stations and plumbing stations
  • Wastewater treatment plants
  • With lakes, streams, wells, and the city water supply, whether or not interconnected with the potable water supply

Plumbing connections that raise concerns for Backflow Prevention

Backflow Assembly Testers 

Backflow Test Form 

Contact Information

Utilities Operations and Maintenance & 24-Hour Emergency Response
Bellevue, WA 98009
Phone: 425-452-7840
E-mail: OMSupport@bellevuewa.gov?cc=whairfield@bellevuewa.gov


Customer Assistance


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