Backflow Prevention

Cross Connection Control

Cross Connection ExamplesIn compliance with Washington State Administrative Code 246-290-490, which regulates the city’s Cross Connection Control Program, Bellevue Utilities inspects drinking water systems on properties to protect against 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. Our goal is to protect your drinking water and the city’s drinking water distribution system.

Customers must have backflow assemblies tested every year

Log-in to our Backflow Assembly Testing Portal to:

  • Check the status of your test(s) submittal
  • Update your contact information
  • Opt-in to receive your notices via email
  • Just send an email to to get your access code!
Translated Backflow Testing Notification Letter
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Frequently Asked Questions

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. 

What are the Dangers Associated with a Cross Connection?

Drinking water systems may become polluted or contaminated through uncontrolled cross connections.  Cross connections are installed each day in the United States because people are unaware of the problems they can create.  Death, illness, contaminated food products, industrial and chemical products rendered useless are some of the consequences of such connections.

Why was Cross-Connection Control established?

The Washington State Department of Health (DOH) Office of Drinking Water is responsible for administering the cross connection control rules for Group A Public Water Supplies, such as the city’s, under the Washington Administrative Code (WAC) section 246-290-490.  Washington established cross connection control reduction programs in 1970. The purpose is to protect the public water system from contamination via cross connections of plumbing systems.  The DOH and public water utilities within Washington State have worked collaboratively to revise our codes and program priorities as we learn more about the dangers of cross connections as they apply to public and private plumbing systems.  As a result, the city is required to develop and implement a Cross Connection Control Program which must be included in the our Water System Plan.

Is there a city ordinance establishing a Cross Connection Control Program?

Yes.  The provisions establishing its cross connection program are codified at BCC 24.02.190, and were adopted in 2010 (Ordinance No. 5693).  The ordinance includes the state’s program requirements and the most recent version of the Uniform Plumbing Code, and is enforceable consistent with BCC 24.02.280. 

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.
Double-check valve
 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

  • Janitor sinks
  • Bidets
  • Hose bibs (inside and outside garden hose faucets)
  • Lawn irrigation systems
  • Lake, stream, well water supplies
  • Laboratory equipment
  • Processing tanks
  • Boilers
  • Water recirculation systems
  • Swimming pools
  • Solar heat systems
  • Fire sprinkler systems

What are the types of backflow prevention devices?

Pictures are for Illustration purposes only.

Double Check Valve Assembly

DCVA – Double Check Valve Assembly / Protection for lower hazards, such as irrigation systems.

Reduced Pressure Backflow Assembly

RPBA – Reduced Pressure Backflow Assembly / Protection for high hazards, such as boilers, x-ray machines, soda dispensers, etc.


Pressure Vacuum Breaker Assembly

PVBA – Pressure Vacuum Breaker Assembly / Protection for lower hazards, such as irrigation systems.


Air Gap

Air Gap – An Air Gap is a physical separation between the free flowing discharge end of a potable water supply pipeline and the overflow rim of an open receiving vessel. Protection for high hazards, such as a chemical tank.
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