Cross Connection/Backflow Backflow through cross connections place the public drinking water (potable water) at risk. Contaminants which could be harmful to health and other objectionable substances can enter the water supply through cross connections. That is why it is imperative that the public is informed about this subject. The term potable water is used to identify water that is safe to drink.

What is Backflow?

Backflow takes place when water flows opposite of its intended direction. There are two conditions that can cause backflow. It may occur due to either backsiphonage or backpressure in the water system. Backflow can take place within any water distribution system whether it is private or public.

What are Cross Connections?

A cross connection is a physical connection between a potable water supply line and a non-potable source (i.e. chemical process water, ponds, lakes or rivers). Under a backflow condition, connections to non-potable sources could potentially cause contamination of our drinking water. Cross connections can jeopardize the safety of our drinking water. A hazardous backflow incident can occur through cross connections when backpressure or backsiphonage conditions exist.

Backsiphonage and Backpressure Cause Backflow

• Backsiphonage can occur when a water main or plumbing system in a building loses water pressure, thus creating a reduced pressure in the water supply piping. This reduced pressure will allow the direction of the water in the system to flow opposite of the normal direction of flow. Such pressure differences can cause siphoning of non-potable water and other liquids back into the potable water lines.
   
• Backpressure occurs when water pressure in a building or fixture becomes greater than the water pressure in the water supply piping. This condition can force non-potable water or other fluids back into the potable water system.

Requirements for Backflow Assemblies

Property owners must:

• Install a backflow assembly if there is an existing or potential cross connection.
• Test the assembly after installation, annually, and if the assembly is moved or repaired, also a requirement of the State Plumbing Code. A State-certified backflow tester must perform the test, and send copies of the test report to the local water provider. The assembly must function properly to pass the test.
• Repair the assembly if it is not functioning properly. A certified tester must retest the assembly after a repair.
• The Water providers can deny or discontinue water service if a property owner fails to follow the law.

Local water providers must:

• Set up and maintain backflow assembly records for water services located inside their distribution system.
• Enforce all state and local laws regarding backflow assembly installation. This includes ensuring that owners test the assemblies each year. The Water Bureau sends annual test notices to backflow assembly owners.
• Send an annual report to DHS. The Water Bureau compiles this report from test reports received from backflow assembly testers.

Can property owners remove their backflow prevention assembly?

The law requires that you notify your water provider before removing a backflow assembly. A water provider inspector will need to inspect the plumbing to verify the cross connection has been eliminated. A plumbing permit may be required to perform this type of work.