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Cross Connection Control Program

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In the interest of protecting the quality of our water, the Louisville City Council adopted a Cross-Connection Control Ordinance on April 19, 2005.

Backflow prevention devices are now required on all commercial, non-single family residential, industrial, institutional, and irrigation connections. Once installed, these devices must be tested annually. The Backflow Prevention Education Council of Colorado provides a listing of these testers by region.

Cross connections occur when the public drinking water supply is physically connected to contaminated sources (e.g., a hose submerged in a bucket or lying on the ground). Cross connections provide a pathway for the backflow of polluted or contaminated water into the drinking water system.

Backflow can also occur when the pressure in the public distribution system drops. Normally this pressure is high enough to prevent backflow; but certain events--such as main breaks, flushing, or firefighting--can lower the pressure enough to allow the water to flow backwards.


The type of backflow prevention device or assembly needed on your system is determined by the level of hazard posed by your water use.

Ingeneral, the City requires the following devices:

Main Water Service: Reduced Pressure Principal Device
Fire Systems
: Double Check Backflow Preventor
Irrigation Systems: Vacuum Breaker


A cross-connection is an unprotected actual connection or a potential connection between a potable water system used to supply water for drinking purposes and any source or system containing unapproved water or a substance that is not or cannot be approved as safe, wholesome and potable. By-pass arrangements, jumper connections, removable sections, swivel or changeover devices or other devices through which backflow could occur shall be considered to be a cross connection.


A backflow device on the incoming line or service is containment. The device is after the water meter, but before any branches or connections to the service line. Containment devices have been installed on service lines of multi-family and commercial accounts since 1984. The State of Colorado regulations require containment devices be tested at least annually. 

A backflow device installed on a residential lawn sprinkler system is an example of an isolation device. This device prevents lawn sprinkler water from getting back into the home.


1. Backsiphonage. A negative pressure that can be caused by water main breaks, fire hydrant flushing or fire fighting. Backsiphonage can draw all the water from a private water system. If this water is used for boiler's, sprinkler systems etc. it could contain contaminated water.

2. Backpressure. This is caused by the pressure in the private water system exceeding the city's water system usually caused by a privately owned pump used to increase pressure inside a single structure. This causes water to be forced back into the city's system.


1. Air Gap -Used mainly on tanks and faucets, it is a gap between the pipe and the container. Requirements:The gap needs to be a minimum 2 times the supply pipe diameter.

2. Atmospheric Vacuum Breaker

Used mainly on lawn irrigation systems. It has an air inlet valve that will drop to draw in air thus preventing sprinkler system water from entering the City's water mains.

  • Not under continuous pressure fro more than 12 hours
  • No downstream valves
  • No backpressure
  • 6" above high point of use

3. Pressure Vacuum Breaker


Used mainly on lawn irrigation systems. It has a one way check and a spring loaded air inlet valve that closes when City water main pressure drops.

  • No backpressure

  • 12" above high point of use

  • Protect from freezing

4. Double Check Assembly


Operates similar to a Pressure Vacuum Breaker. Used on low hazard applications and on fire lines.

5. Reduced Pressure Principle Assembly

Used on high hazard applications and is a combination of check valves and an air inlet allowing water from the private system to vent when City pressure drops.

By installing backflow devices, the possibility of contaminated water returning to the distribution line is prevented.


If you do not have a backflow device:

  1. Call a plumber licensed to do work in the City of Louisville and schedule the installation
  2. Obtain a building permit
  3. After the device is installed, contact the Planning and Building Safety Department's Inspection Request Line at 303.335.4583.

Now that the device is installed:

  1. Contact a company qualified to perform backflow testing and repair. These companies are listed at the Backflow Prevention and Education Council of Colorado web site (
  2. Ask the backflow tester to send a copy of the test report to the Public Works Department, City of Louisville, 1600 Empire Road, Louisville, CO 80027. They may also fax a copy of the report to us at 303.335.4758, attention: Cross Connection Control.

Next year:

The device must be retested. Prior to the anniversary of your test date, you will receive a reminder notice from the City of Louisville. Contact a qualified backflow tester and return the test results to the City of Louisville. Email the results to or fax them to 303.335.4758.

Thank you! You’re doing your part to keep our water clean. For more information about the program, please email or call at 303.335.4750.