Cross Connection Control Program: ​​Backflow Prevention

The City of Moscow is committed to providing quality, cost-efficient service in the production, treatment, testing and delivery of safe drinking water to all of its citizens. Safe and reliable drinking water is a carefully manufactured product. In order to help ensure safe drinking water is always available, the Water Department has implemented a Cross Connection Control Program as required by the "Idaho Rules for Public Drinking Water Systems." (IDAPA

What is a Cross Connection?

A cross connection is any point in the public drinking water system that is actually or potentially connected to a source of contamination or pollution that could enter the system through backflow. Common cross connections include automatic sprinkler systems, soda fountains, fire suppression systems, and garden hoses among many others. All cross connections require backflow prevention.

What is Backflow?

Backflow is water and/or other substances flowing in the opposite direction of the normal and intended course. It is the process by which a cross connection can introduce contaminants into the public drinking water system.

How does Backflow happen?

There are two ways for backflow to occur: backsiphonage and backpressure. Backsiphonage happens when there is a negative pressure in a pipe, causing a vacuum, and water flows in the wrong direction. The vacuum can be caused by high water demand in another part of the system such as from firefighting or a water main break. Backpressure occurs when the pressure at one part of the system is greater than the pressure coming in from the water main. This can happen when a garden hose is connected to a faulty pressure washer, from an overheated water heater or boiler, or from the weight of water on a hill or tall building.

How does this affect me?

In order to protect public health, the City of Moscow has implemented a Cross Connection Control Program as is required by The Idaho Rules for Public Drinking Water Systems​ (IDAPA and the Moscow City Code​ (Title 7, Chapter 9).

The program includes:

· An inspection program to locate cross connections
· Authority to require the installation and operation of adequate backflow prevention assemblies
· A monitoring system to ensure annual testing and inspections of installed assemblies
· Authority to enforce the provisions of the program

The inspection program started by identifying the cross connections with the highest potential danger to public health. Water Department staff continue to identify others which may jeopardize the safety of our drinking water. All new construction projects are evaluated for potential cross connections during the permitting process and required to provide adequate backflow protection when necessary. Notifications are mailed out as a reminder to customers with backflow assemblies four to six weeks in advance of the scheduled due date by which annual testing must be completed. In the case that an assembly is not tested by the due date, subsequent notices are sent which inform the customer that failure to achieve compliance will result in the termination of water service (water will be turned off). Termination of service is an option of last resort. The Water Department will make all reasonable efforts to contact the affected customer and bring them into compliance with state and local regulations.

Lawn irrigation and sprinkler systems

All lawn irrigation systems, commercial and residential, require the installation of an approved backflow prevention assembly. Annual testing, performed by an Idaho Licensed Backflow Assembly Tester, to ensure the assembly is in acceptable working order is mandatory. Failure to comply with these requirements will ultimately result in disruption of water service to the premises.

Water Department personnel will be continuing a street side survey to identify all irrigation systems in the City. A notice requiring corrections to bring these systems into compliance will be sent to the owner(s) of record for systems that have inadequate or non-existent backflow protection. A plumbing permit is required before work can begin and must be purchased at the Building Department. If you are not sure if your irrigation system has a backflow assembly installed, or if you have any other questions about your sprinkler system, contact the Water Department to set up a consultation.

Below is a list of local backflow assembly testers licensed in Idaho and their contact information:

  • Waterworks Irrigation Co., Moscow, ID 208.596.6163
  • Don's Plumbing, Moscow, ID 208.883.8225
  • Goodson Plumbing, Moscow, ID 208.882.5460
  • Carlson's Plumbing, Pullman, WA 509.332.1857
  • Raindrop Sprinklers, Moscow, ID 509.872.2255
  • McCoy Plumbing, Moscow, ID 208.882.2332
  • Aqua Lawn, Moscow, ID 208.882.5634
  • Roto-Rooter, Lewiston, ID 208.746.4282
  • Steve Herres, Pomeroy, WA (509) 843-1232
  • Clearwater Sprinkler Company, Lewiston, ID 208.743.7742
  • Valley Green Sprinklers, Lewiston, ID 208.746.1548
  • Cobblestone Landscaping LLC, Moscow, ID 208.883.2518
  • Umbrella Sprinkler Services, Lewiston, ID 208.798.9115

A garden hose can create a cross connection!

The end of a garden hose can be connected to or come into contact with many potential contaminants. Never submerge hoses in buckets, pools, tubs or other containers as you fill them with water. A hose bibb vacuum breaker is an inexpensive, easy to install device designed to help prevent backflow through your hose. They are available at most hardware stores and home improvement centers.

For questions or for more information regarding backflow prevention, contact Ty Thompson at​ or 208.883.7111.