What Is a Cross-Connection in Plumbing?


Did you know that there is a potential risk for contamination of your drinking water if the wrong type of piping is used in your plumbing system? In this blog post, we’ll explain what a cross-connection is in plumbing and how it can lead to contamination of your water supply.

What is a cross-connection?

A cross connection is a physical connection between two piping systems that allows water from one system to flow into the other. This can occur when two pipes are connected together, or when one pipe taps into another.

Cross connections can be found in both residential and commercial plumbing, and they can pose a serious health hazard. That’s because they provide a direct path for contaminants to enter the potable water supply. If not properly protected, cross connections can allow pollutants to enter the drinking water supply. As a result, it is important to ensure that all cross connections are properly identified and corrected.

Types of cross-connections

Here is a breakdown of the two main types of cross-connections:

Inlet-type cross-connection

This is a type of connection between a potable water distribution system and a receiving vessel (ex: water tank, sink, etc).

One type of inlet-type cross-connection is a gravity-type cross-connection. A gravity-type cross-connection is used for filling a receiving vessel with water. For example, if a sink with an attachment hose is below the overflow rim of the sink, back-siphonage can occur.

Another type of inlet-type cross-connection is a low inlet-type cross-connection. This cross-connection is when a pipe is supplying water near the bottom of a tank. Inlet-type cross-connections will have a submerged inlet.

Direct cross-connection

A direct cross-connection is a physical connection between two piping systems. This connection allows water to flow from one system directly into the other. These connections will be between a potable line and a non-potable line. For example, systems with a shut-off valve can be considered a direct cross-connection. This is because if the valve is not functioning properly, there is a potential for contamination.

What is a cross-connection device?

A cross-connection device is another term for a backflow preventer. Backflow preventers are devices that are installed in order to protect against backflow. These devices work by creating a physical barrier between two water systems. There are several different types of backflow preventers, and the type that is installed will depend on the specific needs of the system.

How can you prevent a cross-connection?

There are a few different ways that you can prevent a cross-connection:

  1. Install a backflow preventer: Backflow preventers are devices that create a physical barrier between two water systems.
  2. Ensure any hoses you use are properly installed: Make sure that hoses are not installed in a way that would allow water to flow back into the potable water system. That means not submerging hoses in tubs, sinks, or toilets.
  3. Use proper piping methods: When connecting two different piping systems, make sure you are properly using transition fittings. These fittings will help to prevent water from flowing between the two systems.
  4. Be mindful of where potential cross-connections could occur: Be aware of any potential cross-connections in your plumbing system. If you have any questions, consult a professional plumber.
  5. Have a plumber inspect your system: Have a plumbing professional inspect your system on a regular basis. They will be able to identify any potential cross-connections and ensure your system is functioning properly.

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