Cross-Connection Control

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Double Check Valve Assembly for landscape sprinkler systemDrinking water is used for a variety of purposes including lawn irrigation, fire suppression and industrial processes. These different uses can result in the contamination of the drinking water system if not protected by a backflow prevention assembly. The goal of the Cross-Connection Control Program is to either eliminate those connections through which contamination may occur, or to protect the drinking water system by installing a backflow prevention assembly.

What is a cross connection?
A cross connection is any point in a plumbing system where there is a direct connection between the drinking water system and a non-potable system.  A common example of this kind of connection is a landscape irrigation system.

What is backflow?
Backflow is the undesirable reversal of flow of water in a plumbing system due to either backsiphonage or backpressure.  Backflow can result in contamination of the water supply through an unprotected cross-connection. 

Backsiphonage occurs when there is a large reduction in pressure within the distributing pipes of the water system which creates a partial vacuum.  A water main break or a large volume of water being used to fight a fire can lead to reduced pressure conditions in surrounding distribution lines. 

Backpressure is a source of pressure, such as pumps or thermal expansion, which exceeds the operating pressure of the potable water supply.  The higher pressure literally pushes the fluid or gas back into the water system.

What are the hazards?
There are two degrees of hazards: high/severe health hazards and low health hazards.  High/severe health hazards are any physical, chemical, biological or radiological substances that may enter the drinking water supply which may result in injury, poisoning or the spread of disease.  A low health hazard or pollutant, is a contaminant which could cause adverse aesthetic problems to the drinking water supply such as taste, odor and color of the water but does not present a danger to public health.

Does backflow really happen?
Yes. Backflow can occur at any time when the conditions are right. There have been hundreds of documented cases of backflow incidents in the United States, even here in the Wenatchee Valley.

Some examples of backflow incidents:

  • A boiler back flowed inside a building and alerted the occupants when hot water was flowing out of the drinking fountains.
  • The CO2 valve failed on a post-mix soda fountain and the resulting backflow caused customers to become sick.
  • An irrigation pump cross connected to the domestic water system back pressuring the potable water supply and filling the main and water services with non-potable water.

For more information on backflow incidents, go to: www.nobackflow.com

What is a backflow prevention assembly?
A backflow prevention assembly is a mechanical device that permits water to flow only in the intended direction.  The assembly prevents the reversal flow of water or other substances from entering the potable drinking water system.  Backflow assemblies are designed to be tested and repaired inline.  They are to be tested upon installation and annually thereafter to ensure that they are functioning correctly and protecting the drinking water system.

Is this a new requirement?
Cross connection control regulations first began in Washington State in 1971.  As directed by the Washington State Department of Health, the City of Wenatchee implemented a Cross Connection Control Program in early 2003 with the passing of Ordinance 2003-03.  The State of Washington Department of Health WAC 296-290-490 is the governing code that requires the city to enforce protection of the public water system from contamination and pollution due to cross connections.

How do I know if I need a backflow prevention assembly?
When a facility or residence has been identified as having a potential hazard to the water system, a survey of the property is performed.  A certified Cross Connection Control Specialist must perform the survey and based upon the finding require corrective action if needed.

My system was installed before backflow assemblies were required, can't it be grandfathered in?
Even with low health hazards there are no exceptions to the requirement of installing a backflow prevention assembly to protect the drinking water system.  Allowing a known cross connection hazard to exist would not only be putting our consumers at risk it is a violation of Washington State Law. 

How much does it cost to install a backflow assembly?
The actual cost of the assembly themselves vary by size and type.  On average, for a modest lawn sprinkling system, backflow assemblies start at approximately $100 and can range to over $8,000 for a large commercial fire sprinkler system.  In addition to the cost of the assembly is the cost of installation.  It is recommended that a licensed and bonded plumbing company install the backflow assembly.  However, for landscape sprinkler systems the homeowner can do the work saving the additional installation expense.

Once installed is there any maintenance associated with backflow assemblies?
Backflow assemblies must pass a test once upon installation and annually thereafter to ensure proper operation.  Only a Washington State certified Backflow Assembly Tester can perform the required test on the assembly.  The cost of this test varies depending on the type and size of the assembly but a DCVA on a landscape sprinkler system usually starts around $35.

 

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