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What Is A Cross Connection In Plumbing


Water is life. Is it right ? No, it’s not.

Because, obviously safe water, not simple ‘water’ is life. Rather contaminated or unsafe water may cause sickness or even death. Safe water is free from all types of germs, harmful bacteria, or contamination. If you want to ensure a disease-free and totally safe life for all of your family members you have to know the plumbing term cross-connection.  

Let’s dive into detail about what is a cross connection in plumbing. 

What is a cross connection in plumbing

In your everyday life, you use tap water from your sink, without ever questioning the quality of your water. As per uniform plumbing code, Cross-connection means ” any actual or potential connection or structural arrangement between a public or private potable water system and any other source or system through which it is possible to introduce into any part of the potable system any used water, industrial fluid, gas or substance other than the intended potable water with which the system is supplied. Bypass arrangements, jumper connections, removable sections, swivel or changeover devices, and other temporary devices through which backflow can occur are considered to be potential unintended cross-connections.”

cross connection Austin's Best Plumbing
Cross Connection

There are so many things or hazards around your house or lawn that could contaminate the water. One of the ways in which your water could be polluted. That is called a cross-connection. It could be very easy to overlook the cross-connection hazard.  

Cross connection can be defined as water flows through the pipelines in the reverse direction, creating, creating what is known as backflow.  

Types of cross connection

Direct and indirect cross connection Austin's Best Plumbing

There are two types of cross connection. Those are:

  • Direct cross connection
  • Indirect cross connection

There are two types of backflow caused by these cross connections.  

back pressure backflow Austin's Best Plumbing
  • Backsiphonage backflow
  • Backpressure backflow

There are two types of backflow conditions  

  • Pollution (low hazard)  
  • Contamination (high hazard)

In direct cross connection there must be a direct physical connection between potable and non-potable water systems.  

Example of direct cross connection is a quick fill line of a boiler.  

There are two types of indirect cross connection

  • Under-rim or submerged cross connection
  • Over-rim cross connection

Water inlet comes into the bottom or side of a holder and is plunged in a polluted or contaminated substance is an under rim or submerged cross connection.

On the other hand, An over-rim connection is a water supply that ends over the overflow measure rim of a fixture, but it has a hose which is probable under rim stop.

Back pressure is such a situation when pressure is greater than that of the water supply. This is dangerous as it can cause potentially contaminated water. The real danger happens when that contaminated water enters your plumbing system by pushing off back pressure.  

Back pressure is possible in residential hot water heating systems.  

In two specific times like when water pressure occurs and the vacuum condition is created are responsible for developing siphon edges.  

This could draw in soapy water, unwanted liquid-like pesticides out of the container through an attached or submerged hose into the drinking water.  

How to prevent cross connection

Plumbers, maintenance, and service workers are primarily responsible to prevent cross-connection. Two things are very important to learn about preventing clean water supply.  

  • Through knowledge about backflow prevention  
  • Installing and testing backflow prevention device or assembly.
backflow prevention device Austin's Best Plumbing

There are some easy ways to protect your home and your neighbors from a cross connection problem.  

First way

Most effective measures can be taken by you to correct these hazards by installing post BIM vacuum breakers on all threaded faucets.  At the time of buying a breaker check for the approved, ASSR 1011 symbols.  

Second way

In the laundry room you must not submerge the end of a hose into a sink or tub that’s connected to a sewer line.

Third way

Do not submerge the end of any holes into buckets, tubs or sinks, and then leave that fully submerged.  At the time using any chemical in the pool or bathroom or kitchen you have to be careful as those could be drawn into safe drinking water.

Fourth way

Toilet is another probable source of backflow problems.  The toilet could be the source of a backflow problem. Never use a hose into your toilet. 

You should use approved ballpark assembly. Those ensure that dishwashers are installed with the proper air gap into devices.  For ensuring cross connection control the state Plumbing code offers a couple of different options.  

You should be proactive and help to save our clean and safe water supply. It’s urgent not for your family, but also all of your neighborhood.  

People Also Asked

What is a cross connection Servsafe?

Ans: A cross-connection Servsafe means a physical connection comes from sewers sink, toilet, drains, or other wastewater to clean and safe drinking water supply. In a simple word, we can say the connection between clean and dirty water is called cross connection servsafe.

What is a cross connection inspection?

Ans: A cross-connection inspection is a process to ensure that there is no cross-connection in buildings plumbing systems. Every building which is connected to the municipal water supply is required to have a cross connection inspection.  

What is the most effective method to prevent backflow?

Ans: The most effective way to prevent backflow is air gap. Air gap is described as a gap, upright or an open space between a water break and flood level of a fixture.  

Do I really need a backflow preventer?

Ans: if you have a safe drinking water connection system, then you must need a backflow preventer because Polluted or contaminated water may cause sickness or even death.  

Where is a backflow preventer located?

Ans: A backflow preventer typically located outside your home or near a business water meter which is in a green or a black plastic box.  

What is the difference between check valve and backflow preventer?

Ans: check valves are designed to flow water or other liquid through only one way. It prevents water or liquid from flowing in the opposite direction. It’s a basic device to prevent cross-connection.  

Backflow preventer devices also have the same features to prevent water flow in a reverse direction. Its task is to keep water or liquid flowing from the water main source to the building’s pipe.

These devices are designed to Prevent flow of water to the next level. Because, it has extra fail-safe saves to keep drinking water pure.  

What is the average time and cost to prevent a backflow?  

Ans: According to the Environmental Protection Agency average backflow incidents require about 500 hours to solve at a cost of $14,800.

Does every house have a backflow preventer?

Ans: Most of the houses which have a sprinkler or/ and an irrigation system installed have a backflow preventer.  

How do I know if I have a backflow preventer?

Ans: By physically looking you can know if you have a backflow preventer. You have to check where water enters your property. Say for your can check the places like the basement by water heater or mechanical room or a crawly place.  Is a vacuum breaker the same as a backflow preventer?

Ans: A vacuum breaker is a tool mainly set up on a flush valve, toilet or a bibcock valve. This tool prevents water siphoned being spilled into the public water system. A more complex valve that accomplishes much the same purpose is the backflow preventer.

How do I know if I have a bad check valve?

Ans: you can know easily if you have a bad check valve. You may notice some activity if this happens. When you see that water runs in the reverse direction after the pump shuts off, the pump will start again at a time when nobody is using water.

How much does it cost to replace a backflow preventer?

Ans: cost to replace a backflow preventer depends on type and size of the system. In general most homeowners spend $135 to $1000 .  

Let’s break down the cost item’s: 

Device itself $35 to $600, 

Professional labor cost $100 and $400.

Why is backflow bad?

Ans: backflow is bad because it may cause sickness even death for users of water. By backflow bacteria, harmful chemicals and other contaminated materials can enter through cross-connections, into safe public water supply. That is so dangerous for life as I mentioned earlier. It’s a serious public health hazard.  

Do I need a vacuum breaker?

Ans: if you already have one built sillcocks in your vacuum breaker, then you must not need a new one. On the other hand, if there is no little mushroom cap in the sillcock, then an external vacuum is required.  

A vacuum breaker is also needed for a laundry sink faucet, if there are threads present to attach a garden hose.

What are the different types of backflow preventers?


  • Backflow Prevention Devices.
  • Atmospheric Vacuum Breakers.
  • Backflow Prevention Assemblies.
  • Pressure Vacuum Breakers.  
  • Spill-Resistant Vacuum Breakers.  
  • Double Check Valves.
  • Reduced Pressure Principle Backflow Assembly

Do backflow preventers have to be above ground?

Ans: yes, it’s recommended to install backflow preventer above ground. This is for purity of public drinking water. If any backflow preventer is installed below ground, then it may fill with bacteria, germs and/ or contaminated water.  

Does an RPZ reduce pressure?

Ans: Elaborate form of RPZ is Reduced Pressure Zone. If you want to open as well as dump water out of any system, then you should install a RPZ. This is not for allowing bacteria, germs, or contaminated water to backflow into the safe water supply.

Can I install my own backflow preventer?

Ans: For a new installation or a replacement where plumbing task is necessary, a plumbing permit from the concerned authority is also required. In the same way, you require to have a backflow permit before doing the work.

How long do backflow preventers last?

Ans: Normally backflow preventers last more than fifty years.  


Now you have learnt about what is a cross connection in plumbing. Hope this will help you to avoid unexpected situations.  

Austin’s best plumbing company plumberson’s goal is to help you to have safe drinking water. That’s why we are here to evaluate the risk of cross-connection and troubleshooting with the use of the right tools.  

Please call Austin’s best plumbing company plumberson to have assistance or advice about Cross connection.  

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