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Cross Connection—
Frequently Asked Questions

Why Be Concerned?

Faucet

Most water systems in the United States have good sources of water or sophisticated filter facilities to convert non-potable water into potable (drinkable) water to meet the Environmental Protection Agency Drinking Water Standards. Many millions of dollars are spent to make non-potable water into potable water before it enters the distribution system.

Most water purveyors think that their water is not in jeopardy from this point on. Studies have proven this to be wrong. Some water systems have become contaminated through plumbing connections that allow contaminates to enter the system. These connections are often referred to as "cross connections".

Cross connections are installed each day in the United States, mostly by plumbers or professional water people who are unaware of the problem they can create. Some of the hazards of such connections can be, disabling illness, contaminated food products, industrial and chemical products rendered useless and in some extreme cases, death. As a result, many hours and dollars are lost due to a lack of understanding of the hazards associated with cross connections.

What Is a Cross Connection?

A cross connection is a point in a plumbing system where the potable water supply is connected directly or can be connected directly to a non-potable, potentially lethal source. Wherever an unprotected cross connection exists, backflow may occur due to either "backsiphonage" or "backpressure", and pathogenic microorganisms can be carried into the potable water supply. Backsiphonage is caused by a negative or reduced pressure in the supply line to a facility or plumbing fixture. The principle causes of backsiphonage are:
  1. High velocities in pipe lines that create a "venturi" effect.
  2. Water main line repair or break which is lower than a service point.
  3. Lowered water main pressure due to high water withdrawal rates such as fire fighting or water main flushing.
  4. Reduced water main supply pressure on suction side of a booster pump.
Backpressure may cause backflow to occur whenever a potable water system is connected to another system operating at a higher pressure. The principal causes of backpressure are:
  1. Booster pumps in the private plumbing system designed without backflow prevention assemblies.
  2. Potable water connections to boilers and other non-potable pressure systems.
  3. Interconnection with another plumbing system operated at a higher pressure.
  4. Water piping extending 30 feet above finished grade.

Where Are Cross Connections Found?

Faucet Whenever a plumbing fixture is connected to the potable water supply, a potential cross connection exists. Fortunately, many of the plumbing fixtures have built -in backflow protection. Listed below are some of the cross connections found in water systems:
  1. Wash basins and service sinks
  2. Hose bibs
  3. Irrigation or lawn sprinkler systems
  4. Auxiliary water supplies (wells)
  5. Laboratory and aspirator equipment
  6. Processing tanks
  7. Boilers
  8. Water recirculating systems
  9. Swimming pools
  10. Solar heat systems
  11. Fire sprinkler systems

As you can see, every water system has cross connections. The City of Beaverton has a cross connection control program as required by the State of Oregon Health Division Drinking Water Section. This program is a combined effort between our plumbing inspectors and our cross connection inspector. It includes the elimination or protection of all cross connections, when found, by approved methods or approved equipment called backflow assemblies. The different types of methods or backflow assemblies used are based on what is known as the degree of hazard.

Some facilities, due to their water sues, are required to have mandatory backflow protection installed on their water service connection. The following is a brief list of conditions with varying degrees of hazard:

  1. An auxiliary water supply
  2. Piping for conveying liquids other than potable water
  3. Intricate plumbing which makes it impractical to ascertain if cross connections exist
  4. Backsiphonage potential
  5. Sewage treatment plants
  6. Sewage pumping stations
  7. hemical manufacturing plants
  8. Hospitals and medical clinics
  9. Mortuaries
  10. Car washes

Frequently Asked Questions

Why do I have to install a backflow prevention assembly?
To protect the customers of public water providers, the Environmental Protection Agency Safe Drinking Water Act, State of Oregon Health Division, and Uniform Plumbing Code each require that cross connections be equipped by the customer with backflow protection. Therefore, the City of Beaverton has adopted codes, which regulate cross connections.

Does the backflow prevention assembly have to be tested?
Most backflow prevention assemblies are required to be tested upon installation, when repaired, moved and annually thereafter. A tester who is certified by the State of Oregon Health Division must do the testing. The annual testing of backflow prevention assemblies ensures that the assembly is working properly to protect against backflow.

Does the City of Beaverton test the backflow assemblies?
No, the City of Beaverton does not test its customers' backflow prevention assemblies. Instead, the City allows its customers to retain the services of a certified testing firm to perform the test.

What types of backflow assemblies are required to be tested?
Reduced Pressure Principle Assemblies, Double Detector Check Assemblies, Double Check Assemblies, Pressure Vacuum Breaker Assemblies and Spill Resistant Vacuum Breakers are required to be tested.

Why do I have to install a backflow assembly on my lawn sprinkler system?
A lawn sprinkler system is considered a non-potable water use. The water in these Systems can become contaminated by lawn chemicals which are applied on the Ground, animal waste, or the water can become stagnant. Also, water that is Contaminated with toxic substances or pathogenic organisms can be backsiphoned through a leaky valve and endanger the health of a household, neighborhood, or the entire community.

What is the most common type of cross connection found?
The garden hose is the most common cross connection. Garden hoses are used for many things and are often connected to sprayers for lawn chemical addition or cleaning drains or left lying where drainage accumulates. With a sudden drop in system pressure, backsiphonage will occur.

Who is liable in the event of backflow contaminated water into the public water system?
There have been cases where fault has been proven and damages collected from the person who created the cross connection.

As you can see, the Cross Connection Control program is a complicated, but vitally important program. If you have any further questions please feel free to contact our Cross Connection Control Inspector, John Mitchell, in our Engineering Division at (503) 350-4042.


Cross Connection Information