Cross Connection

Introduction to Cross Connection and Backflow Prevention

We work hard as your local water and wastewater management utility company to ensure that the water delivered to our customers is free from contamination. But once water passes through our water mains our customers can do their part to ensure clean water.

Water, like electricity, always takes the path of least resistance, traveling from areas under high pressure to areas under lower pressure. Under normal conditions, the water we provide travels in one direction: from our water main towards your property. But under irregular conditions, like a water main break or a broken fire hydrant, the water can be forcibly siphoned back into the system. This is known as Backflow and backflow occurs through a Cross Connection.

A Cross Connection is a point where the potable water supply is connected to a non-potable source.  Pollutants can enter the safe drinking water system through uncontrolled cross connections when backflow occurs.  Backflow occurs when a backsiphonage, or backpressure, condition is created in a water line. Backflow prevention devices keep this from happening.

Backsiphonage may occur due to a loss of pressure in a water distribution system during a water main break or repair.  A reduction of pressure below atmospheric pressure creates a vacuum in the piping.  For example, if a hose bib was open and the hose was submerged in a wading pool during these conditions, the non-potable water in the pool could be siphoned into the household plumbing and back into the community water system.

Backpressure may be created when a source of pressure, such as a pump, creates a pressure greater than that supplied from the Utility’s distribution system. If a pump supplied from a non-potable source, such as a pond or an untested private well, were accidentally connected to the home plumbing, the non-potable water could be pumped into the community water system.

Water that is in the pipes on the property owner's side of the meter can be exposed to many outlets and fixtures: sinks, irrigation systems, washing machines, spas, swimming pools, solar systems, buckets of soapy water, pools of water on the ground, hose bibs, and commercial fixtures like boilers and cooling towers - all of which can be exposed to chemicals and other contaminants.

Backflow prevention devices are like safety belts, protecting you from events that may never happen.  The key to protecting our drinking water is having proper backflow prevention measures in place to guard against potential hazards and making sure backflow prevention devices are regularly maintained and tested as required.

Customer Service Inspections are required for all applicants for new service connections or facilitates which have undergone extensive plumbing modifications. The inspection certificate shall certify that the establishment is in compliance with the Texas Commission on Environmental Quality (TCEQ) Rules and Regulations for Public Water Systems, Section 290.46(j).  Corix Utilities Texas is not required to perform these inspections for the applicant/customer, but will assist the applicant/customer in location and obtaining the services of a certifies inspector. 

Please contact one of our Cross Connection Specialists for help in determining which type of backflow prevention assembly is acceptable in your region. 

Customer Service Inspection Form

Customer Service

For residential water customers that were requested to return the Cross-Connection Questionnaire, you may complete the survey for the physical property for which water service is being provided by clicking the following link:

For commercial water customers that were requested to return the Cross-Connection Questionnaire, you may complete the survey for the physical property for which water service is being provided by clicking the following link:

For Examples of Past Cases of Cross Connection and Backflow Events please visit:


WARNING: Installation of a backflow prevention device could cause thermal expansion resulting in potential serious bodily injury and/or property damage. When installing a backflow prevention device, you must consult with a professional plumber to protect against thermal expansion AND ENSURE ALL NECESSARY PRECAUTIONS ARE TAKEN. For more information on thermal expansion, please visit our Thermal Expansion section under Cross Connection Control and Backflow Prevention in this website.