Backflow & Cross Connection
Backflow is the plumbing term for an unwanted flow of water in the reverse direction.
When you connect to the City of Ridgefield water distribution center, the intention is for the water to flow from the system to the customer. However, the flow of water could be reversed from the customer back into the distribution system. If cross-connections exist within the customer's plumbing system when this backflow occurs, then it is possible to contaminate the public water supply.
There are two types of backflow.
Backpressure backflow occurs when the pressure of the nonpotable system exceeds the positive pressure in the water distribution lines; that is, the water pressure within an establishment's plumbing system exceeds that of the water distribution system. For example, the pressure in a hot water boiler system increases to a point that it exceeds the pressure in the water distribution system, a backflow from the boiler to the public water system may occur.
Backpressure can result from an increase in downstream pressure, a reduction in the potable water supply pressure or a combination of both. Reductions in potable water supply pressure occur whenever the amount of water being used exceeds the amount of water being supplied, such as during water line flushing, fire fighting or breaks in water mains.
Backsiphonage occurs when there is a partial vacuum (negative pressure) in a water supply system, which draws the water from a contaminated source into a potable water supply. The effect is similar to siphoning or drinking water through a straw.
For example, during a large fire, high flows of water are pumped out of the distribution system through a fire hydrant. This can result in significantly reduced water pressure around the withdrawal point and create a partial vacuum in the system, causing suction of contaminated water into the potable water system. During such conditions, it is possible for water to be withdrawn from nonpotable sources located near the fire hydrant. Air-conditioning systems, water tanks, boilers, fertilizer tanks and washing machines are possible sources of backsiphonage.
Backflow Prevention Devices
A backflow preventer is a method or mechanical device to prevent backflow and provides a physical barrier to backflow.
The City of Ridgefield's Cross Connection Control Program requires any customer who has a backflow prevention device to test their backflow assemblies:
- After initial installation
- After any repair, replacement or relocation
- Annually by a certified backflow assembly tester
Annual inspection of Backflow prevention devices is mandated by RMC 13.55.040.
As a courtesy, our Public Works Department sends reminder letters when it is time to have your backflow assembly tested.
The city's letter notification cycle is April through September. Annual testing is required per the Department of Health WAC 246-290-490(5)iv. If you recently built a house and have a backflow assembly on your premises, the next test will become due between April and September of the following year.
You can find a current list of City Approved and Certified Backflow Testers at the top of this page. Please note, this list is provided as a convenience only and is not intended to endorse or recommend a particular service.
A cross-connection is any temporary or permanent connection between a public water system or consumer's potable (i.e., drinking) water system and any source or system containing non-potable water or other substances.
Examples of Common Cross Connections
- Hot tubs
- Auxiliary water systems (wells)
- Hoses submerged in polluted or contaminated water
- Water (from a well or pond) pumped into an irrigation system directly connected to the water supply system
- An underground lawn sprinkler system directly connected to the water supply system
- A fountain or swimming pool directly connected to the water supply system for filling
City and State Requirements Protect Our Community's Water Supply
If you have or are planning on installing an irrigation system, you must first comply with state and local laws. These laws require that all irrigation systems have approved backflow protection. A plumbing permit is also required when installing an irrigation system. Without proper backflow protection, your irrigation system could endanger the health of your family, neighbors, and others in the community who are using the public water supply system.
Testers are required to enter their test reports in our web test portal. Usernames and passwords have been provided by the City. If you have forgotten your login credentials send an email to the City requesting your username and password.
For more information on the Web Test Portal please see Related Documents.
For more information regarding cross connection please contact the City's Cross Connection Coordinator at 360-857-5010.
A New Way to Submit Tests
- Test the backflow assembly
- Log into the Web Test Portal
- Enter the serial number and the house number to locate the backflow assembly
- Enter test results (on a simple test entry screen)
- Enter suggested changes, e.g. model, size, serial number (if appropriate)
- Click submit and pay the fee
- Print a completed test report for the customer (optional)
Redefine the Paperwork
Enter test results in the field using a tablet with a Wi-Fi connection or a smartphone. Upload them in the field or wait until you are back in the office, or 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. The website confirmation number is all you need to confirm the tests have been uploaded to the utility.
- Why is backflow prevention important?
- I received a letter saying I need to install a backflow preventer. How do I do that?
- I am a renter. Why did I receive a letter about the backflow preventer?
- I received a letter to test my backflow preventer at a home/property I sold previously. How do I update my information?
- Why do backflow preventers have to be tested each year?