Cross Connection Policy

4/24/17: TGW has a new Cross Connection Policy P016 attached at the bottom of the page:

The California Code of Regulations Title 17 requires public water suppliers to protect their water systems from cross-connections and prevent backflow situations. 

Member Responsibility

TGW members are responsible to ensure the elimination or protection of all cross-connections on his/her premises.  The members are responsible for assessing his/her premises for potential cross connections and having the proper device installed as necessary.  Where Member Backflow Prevention Devices & Assemblies are installed they need to be tested each year to ensure they are working properly.  A licensed backflow tester must perform the testing.  Existing backflow prevention assemblies, on properties, are to be continually maintained and tested regardless of change of occupancy.  

TGW Responsibility

TGW is responsible for the prevention of water, which has passed out of the TGW Water Distribution System, from coming back into the system potentially contaminated.  Where TGW finds a cross connection problem, TGW may require a back flow prevention device or assembly or discontinue or refuse to any premises where there exists a cross connection in order to protect the TGW Water Distribution System.  TGW's responsibility ends at the water meter, therefore, it is prudent for TGW to require proper protection of the water system.

Learn more about Cross Connection below:



It is a logical assumption that because water is always under pressure, it can only flow in one direction.  however, can it flow the opposite way from its intended direction?  The answer is yes, and when it does it can sometimes cause disastrous results!  Water will always flow toward the point of lowest pressure.  If a main line in our system should break or If a fire occurred and the fire pressure in the water mains drop dramatically it can cause a reversal of water flow pulling water from whatever water lines are attached to it and is why TGW is concerned about the possibility of backflow of contaminants into our drinking water distribution system.  Below are some scenerio's to be aware of:
  • If your water hose is submerged in your swimming pool, jacuzzi, pond, fountain, or car radiator and a main breaks, that hose could siphon the non drinkable water material back into our water mains!! 
  • The garden hose is the most common cross connection in the home.  It acts like an extension of the water line.  The hose is attached to the outdoor faucet and the other end is connected to an aspirator that contains insecticides, fertilizer or other chemicals used with the aspirator. 
  • If your plumbing carrying drinking water is connected to piping carrying fluid such as an air conditioner containing chemicals to kill algae, the contaminant could be drawn back into our water mains.
  • If you have a private well that is connected to the indoor plumbing is higher water pressure than the water system main pressure, that well water can contaminate the water system.

  • You can install a hose bibb vacuum breaker to prevent any back siphonage.
  •  If you have a water tank, make sure that it has an Air Gap device.

Sprinkler backflow prevention:
Backflow Prevention applications:
Cross Connection Control:
What is Backflow:

Patricia Newby,
May 27, 2015, 5:58 PM
Patricia Newby,
Apr 26, 2017, 9:11 AM