Backflow Prevention

The City of Saint Charles strives to provide you with safe and reliable drinking water. This effort begins with protecting supply sources and continues through the entire distribution process until the water reaches your service line. The prevention of backflow into the public water supply is an integral part of ensuring safe drinking water.  Backflow devices are required to be tested annually. Failure to have backflow devices checked annually could result in water service interruption for the customer. 

The water distribution system is designed to allow water to travel in one direction, from the treatment plant to the customer. When a sudden loss of pressure occurs in the distribution system, water can flow in the opposite direction from the normal flow. This unwanted process is known as backflow. When this occurs, potentially harmful contaminants can mix with drinking water and threaten the safety of the City water supply.

Backflow prevention devices are valves that prevent water from your home or business from going back into the City's water system. Irrigation systems are the first priority for backflow prevention programs because of the possibility of contamination from lawn chemicals, pet waste or other pollutants.

The City of Saint Charles manages an active backflow and cross-connection prevention program. This program is required under state and local plumbing codes and is designed to prevent the possible contamination of the public water supply through backflow from customers’ facilities. Failure to maintain and test a required backflow prevention device could result in water being shut off for non-compliance.

Backflow Solutions, Inc (BSI) manages the City of Saint Charles cross connection control program (backflow prevention). BSI was founded with the express purpose of working with irrigation professionals, and water purveyors, to provide exceptional backflow management solutions. The BSI team is comprised of backflow industry professionals, with expertise in cross-connection control management. With a web-based tracking program called BSI Online, BSI provides an efficient and cost effective means of managing the city’s inventory of backflow prevention assemblies. BSI charges testing companies $12.95 for each device.

BSI will mail a letter to the owner of the backflow device 30 days prior to the expiration of the 1 year anniversary of the testing. If BSI does not receive an updated test report online, from a certified tester, BSI will mail a second letter to the owner that they are non- compliant. A third letter will be sent by the City informing the owner that per Missouri state law, and City ordinance, their water will be shut off until they submit an updated test report.

For questions regarding your backflow prevention device test, please contact BSI Online at or at 800-414-4990.

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