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30 Oct 2014  
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Cross Connection and Backflow Prevention


REMINDER:
All Tigard Water Service Area customers are required to have their backflow prevention devices tested each year by June 1.
If you have a lawn irrigation system, then you also have a backflow prevention device. This important device protects our water supply from contamination. Because backflow prevention devices have internal parts that can wear out, the Oregon Health Authority requires these devices to be tested annually (see OAR 333-061-0070(5)). A person who is state-certified in backflow assembly testing must perform the test and send the results to the City of Tigard.



Did You Know...
It is estimated that nearly 1.1 billion people don't have access to safe drinking water. In the United States, where drinking water is among the safest in the world, it's easy to take water for granted. And even though providing safe, clean drinking water may seem effortless, the act of obtaining, treating, storing and delivering quality water is a complex undertaking.

Water users may be surprised to learn they play an essential role in maintaining safe, clean drinking water. By preventing pollutants and contaminants from entering the drinking water system, water users help to protect the quality of the water for themselves and their community.

Cross Connection and Backflow at Your Fingertips

The Basics
Backflow Prevention Assemblies
Installation
Testing

The Basics

What is a cross connection?
Cross connection refers to an actual or potential link between the drinking water system and contaminants, such as chemicals, bacteria, pesticides, or waste water.

Examples:
  • A garden hose is submerged in a bucket of soapy water, hot tub, or swimming pool.
  • A lawn irrigation system is connected directly to the drinking water system.
What is backflow?
Backflow occurs when water flow is reversed from its intended direction and, by way of a cross connection, is pushed or siphoned back into the drinking water system. Backflow can occur by the following mechanisms:
  • Backsiphonage - The pressure in the drinking water system is lowered. This type of backflow can result from water line flushing, fire fighting, or water main breaks.
  • Backpressure - The pressure in a customer's piping system is greater than that of the drinking water system. This primarily occurs in commercial applications involving pumps, high rise buildings, or boilers.
Examples:
  • A garden hose submerged in a bucket of soapy water, hot tub, or swimming pool creates a cross connection. This allows the contaminated water (soapy water or chemically treated hot tub or pool water) to be backsiphoned into the water system.
  • Water containing lawn chemicals is backsiphoned into the water system by way of a lawn irrigation system.
How can cross connections and backflow affect my drinking water?
If a cross connection exists and backflow occurs, contaminants can be drawn back through pipes and into the drinking water system. This has the potential to pollute drinking water and create a potential health hazard.

Examples:
  • A garden hose is submerged in a bucket of soapy water. A water main breaks down the street, lowers water pressure, and soapy water from the bucket is backsiphoned through the hose and into the water system (backflow). At the same time, someone at the residence pours a glass of water from the kitchen faucet. The soapy water flows back out the kitchen faucet, creating a contaminated glass of water.
  • A sprinkler head from a lawn irrigation system sits in a puddle of water containing fertilizer (cross connection). Two blocks down the street, firefighters connect to the water system to fight a fire and water pressure is lowered. The puddle of water containing fertilizer is backsiphoned through the sprinkler head and into the water system (backflow.) Meanwhile a neighbor is taking a shower. The fertilizer-contaminated water flows back through the water system and out the neighbor's shower head.
What can I do to prevent backflow?
The easiest way to avoid backflow is to eliminate cross connections between the drinking water system and contaminants. Sometimes cross connections cannot be avoided. In these cases, the installation of a backflow prevention device will stop backflow.

Examples:
  • Avoid creating a cross connection when filling a bucket, hot tub or swimming pool. By leaving a gap between the hose and the water in the container, you eliminate the cross connection and the possibility of backflow.
  • Install a backflow prevention device between the lawn irrigation system and the drinking water system to prevent backflow.
Backflow Prevention Assemblies

What is a backflow prevention assembly?
A backflow prevention assembly is a mechanical valve arrangement, which prevents the reversal of water flow, once it has passed through the valve. There are different types of backflow prevention assemblies for different situations and different degrees of hazard. (See OAR 333-61-0071 for Backflow Prevention Assembly Installation and Operation Standards)

When is a backflow prevention assembly required?
Anytime a connection to the water system is made, the City's Permit Center should be contacted to determine backflow prevention requirements. The Permit Center is located at 13125 SW Hall Blvd. in Tigard and can be reached at 503-718-2439.

Examples:
A backflow prevention assembly may be required if you have a:
  • Lawn irrigation system
  • Hot tub
  • Water feature such as an ornamental fountain or fish pond
  • Swimming pool or spa
  • Solar heating system
City code prohibits any type of cross connection which could endanger the water system. Cross connections are regulated by both the Oregon Health Authority and the City of Tigard.

What are the different types of backflow prevention assemblies, devices, and methods?
Air Gap (AG): An AG is a physical separation between the end of the discharge pipe and the flood level rim of the container being filled. The separation must be two times the diameter of the opening of the discharge pipe. This is the highest form of protection, since the drinking water supply is physically separated from the container.

Atmospheric Vacuum Breaker (AVB): An AVB is a non-testable device consisting of an air inlet valve or float check, a check seat and an air inlet port(s). This device is designed to protect against a non-health hazard or a health hazard under a backsiphonage only. Product and material approval is under the Oregon Plumbing Specialty Code.

Reduced Pressure Principle Assembly (RP): An RP is a mechanical valve assembly consisting of two internally loaded, independently operating, check valves and a mechanically independent, hydraulically dependent relief valve located between the check valves. It is used for services having either health hazards or non-health hazards and under conditions of backpressure or backsiphonage and gives the highest level of protection among the mechanical backflow prevention assemblies.

Double Check Valve Assembly (DCVA): A DCVA is a mechanical valve assembly consisting of two internally loaded, independently operating, check valves together with tightly closing resilient seated shut-off valves upstream and downstream of the check valves. It is used for services having non-health hazards and under conditions of backpressure or backsiphonage, usually for fire suppression systems.

Pressure Vacuum Breaker (PVB): A PVB is a mechanical valve assembly that includes a check valve, which closes with the aid of a spring when water flow stops. It also has an air inlet valve, which opens when the internal pressure exceeds atmospheric pressure, preventing backsiphonage. It is used for services having either health hazards or non-health hazards and no backpressure conditions; it is typically used on irrigation systems.

Double Check Detector Assembly (DCDA): The DCDA is a mechanical valve assembly consisting of two DCVAs, one that is line sized to provide full flow characteristics and one which is smaller (either " or ") located on a detector line. It is used for services having non-health hazards and under conditions of backpressure or backsiphonage, usually for fire suppression systems.

Reduced Pressure Detector Assembly (RPDA): The RPDA is a mechanical valve assembly consisting of two RPs, one that is line sized to provide full flow characteristics and one which is smaller (either " or ") located on a detector line. The RPDA is used on fire suppression systems which pose a health hazard.

Installation

Do I need a permit to have a backflow prevention assembly installed and is there a permit fee?
Yes, a plumbing permit is required to install a backflow prevention assembly. Permits can be obtained through the City's Permit Center, 13125 SW Hall Blvd., Tigard. For permit fee information, contact the Building Permit Technicians at 503.718.2439.

Who can install a backflow prevention assembly?
The property owner, a licensed plumber, or a landscape contractor licensed to install backflow prevention devices. A plumbing permit is required.

What does it cost to install a backflow prevention assembly?
Backflow prevention assembly installation is done by private companies who set their own rates. Installation costs vary, so getting quotes from several companies is recommended.

Testing

Why am I required to have my backflow prevention assembly tested?
Backflow prevention assemblies have internal seals, springs, and moving parts that wear out. Regular testing is required to ensure backflow prevention assemblies are functioning properly and have not been bypassed. A visual check of air gap assemblies is sufficient, while mechanical assemblies must be tested with special equipment.

How often do backflow assemblies need to be tested?
All backflow prevention assemblies must be tested at least annually and immediately following any repair, maintenance, or relocation. Assemblies that repeatedly fail may require more frequent testing or replacement.

Who is responsible for the testing and maintenance of the backflow prevention assembly?
It is the responsibility of the property owner to ensure the assembly is in good operating condition. A person who is state-certified in backflow assembly testing must perform the test and submit the results to the City of Tigard. If any repair work or maintenance is performed, the assembly must be retested immediately. All test results must be submitted to the City of Tigard within 10 days.

The Certified Tester should mail original test results to the City at:
City of Tigard
Water Division - Cross Connection Program
13125 SW Hall Blvd.
Tigard, OR 97223

What is a Certified Backflow Assembly Tester and how can I find one?
A Certified Backflow Assembly Tester is someone who has completed a state-approved, 40-hour training course in backflow prevention assembly testing and has passed a proficiency test to prove his/her knowledge. Many plumbing, fire sprinkler, and lawn irrigation companies, as well as backflow prevention testing companies, are listed in local telephone directories and provide testing services in the Tigard area. As a convenience, the City of Tigard maintains a partial list of companies offering the services of Certified Backflow Assembly Testers.

What does it cost to test a backflow prevention assembly?
Backflow prevention assembly testing is done by private companies who set their own rates. Testing costs vary, so getting quotes from several companies is recommended.

What happens if I do not have my backflow prevention assembly tested and maintained as required?
Oregon Administrative Rules (OAR) Chapter 333-61-070 mandate the City of Tigard establish and maintain a cross connection control program. The OARs and the Tigard Municipal Code, Chapter 12.10.110, require the City to terminate water service should a property owner fail to comply with cross connection regulations. This includes testing and maintenance of backflow prevention assemblies.

For more information regarding cross connection and backflow, please contact hung@tigard-or.gov, Cross Connection Specialist or phone 503-718-2603.

 
Importance of Backflow Prevention
Blisters in Alabama
The story of a water system contamination incident in Alabama where sodium hydroxide entered the public water system causing injury to people.

Fire and Explosion in Connecticut
Hundreds of people were evacuated from their homes and businesses on an August afternoon in a town in Connecticut in 1982 as a result of propane entering the city water supply system.

Backflow Incident Car Wash
Soapy water from a car wash system contaminated public water system.

For More Information
Download our Informational Brochure

* Visit the Oregon Health Authority website

View the Oregon Administrative Rules

* Contact Hung Nguyen, Cross Connection Specialist, hung@tigard-or.gov, or 503-718-2603






CONTACT US
City of Tigard, 13125 SW Hall Blvd, Tigard, OR 97223
Automated Phone Attendant: 503-639-4171
Additional Contact Information | Map and Directions | Location and Hours of Operation


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