What Is a Plumbing Cross-Connection Survey and Why Backflow Testing Matters for Your Facility

Clean water is absolutely critical to a building’s safety. Two of the biggest threats to the water quality of a plumbing system, whether it’s commercial or residential, are cross connections and backflow. To continue providing clean water and stay in compliance with DNR regulations, facility managers and owners need to be well versed on these dangers and know how to find a contractor you can trust to conduct a cross-connection survey and backflow testing.

What Is a Plumbing Cross-Connection Survey, and How Do I Conduct One?

A cross connection is any place where a plumbing system’s potable water meets, or could potentially meet, a source of contamination. Cross connection is of a greater concern in commercial buildings where water is used in ways other than consumption, such as industrial processes like cooling towers or appliances like boilers. To learn more about possible cross connections at your facility, request an inspection with an Ahern specialist.

A cross-connection survey is a thorough and methodical evaluation of the water-system piping in a building, starting at the water source and ending at the last free-flowing tap. Cross-connection surveys are a major preventative tactic against the contamination of drinking water. These surveys are performed by certified cross-connection control specialists or plumbers.

To conduct a cross-connection survey, the inspector will first map out the building’s entire water system, including all fixtures and equipment that use water. Then, they will analyze each point on the map for any real or potential contamination or pollution. The final result of this research is a detailed survey that includes all hazard points as well as steps the building proprietor can take to correct the hazards.

Common Cross-Connection Plumbing Issues and How To Avoid Them

Any building with plumbing systems utilizing both potable and nonpotable water present a risk of cross connection. Knowing where vulnerable points are in your building is essential for safety. Over our decades of plumbing and cross-connection surveying experience, Ahern specialists have identified several common areas where cross connections are most likely to appear in commercial buildings.

1. Outdoor Connections
   • Problem: Too often, we see outdoor connections like water hoses left in hazardous positions such as in pools, in buckets full of chemical solutions, or connected to chemical sprayers. When pressure drops in the main line, there is a risk that these contaminants get siphoned into the building and into the potable water system.
   • Solution: Hose bib vacuum breakers are an inexpensive and effective tool to prevent back-siphonage. In many states, including Wisconsin, they are required in state plumbing codes. And as a general rule, we highly recommend never leaving a hose submerged in liquid.
2. Heating Systems
   • Problem: Heating systems like boilers and water heaters use chemical additives to prevent corrosion and scale buildup. While integral to the performance of the system, these chemicals also pose a cross-connection risk. If the heating system’s water line is not carefully protected, these chemicals can leak into the potable water supply.
   • Solution: Install a reduced pressure zone assembly or backflow preventer on the heating system’s water line to prevent chemical contamination. The part you need is dependent on your specific equipment and plumbing system; talk to an Ahern cross-connection specialist to determine what will work best in your building.
3. Irrigation Systems
   • Problem: Underground irrigation systems like pop-up sprinklers and surface drip irrigation can endanger the potable water supply because of their direct contact with soil and all of the fertilizers, chemicals, and pesticides within the soil.
   • Solution: Installing the appropriate backflow preventer, such as a vacuum breaker or RPZ (reduced pressure zone) assembly on your irrigation water supply line will ensure water pressure and flow operates as intended. In many states, including Wisconsin, RPZ assemblies are already required by the DNR.
4. Fire Protection Systems
   • Problem: Over time, fire protection sprinkler systems can become contaminated with stagnant water, which introduces rust and bacteria. This contamination is a major risk to potable water systems if the systems are connected.
   • Solution: In addition to regular system testing, installing an RPZ or DCVA (double check valve assembly) device on the fire system connection will block cross connection.
5. Industrial Process Water
   • Problem: Manufacturing plants, medical facilities, and laboratories all use processes that create contaminated water as a derivative. This water can contain a wide range of harmful chemicals and waste products; it is an extremely high-risk cross-connection hazard.
   • Implementing a point of use (POU) backflow preventer and regularly inspecting its functionality will prevent water contamination.

What Is Backflow Testing and How Does It Work?

Backflow is another danger to a potable water system. Backflow occurs when water flows in the opposite direction than intended. There are a two common causes for backflow:

• Backpressure: This happens when the water pressure downstream (the area of the plumbing system past a point of interest) becomes greater than the supply pressure (the force that pushes water through your pipes) and directs the water to flow backwards and potentially into potable water.
• Backsiphonage: When supply pressure drops during a high water withdrawal event, such as a water main break or fire hydrant use, it creates a vacuum that can draw contaminated water back and into the potable water system.

In order to prevent contamination, building facilitators in many states – including Wisconsin – are required to install backflow prevention devices in all areas vulnerable to potable water contamination. These devices are one-way valves that stop water from flowing in the wrong direction. Backflow preventers must be tested upon installation and annually afterwards (or more frequently if desired) by a licensed Cross Connection Control Tester.

During the backflow device testing process, the tester shuts off the downstream water and checks the water pressure and the valves to identify any leaks or malfunctions in the device.

Cross-Connection Survey vs Backflow Testing: Know the Difference

Cross-connection surveys and backflow testing both aim to spot potential potable water contamination, but there are some key differences to be aware of.

Frequently Asked Questions about Cross-Connection Plumbing and Backflow Testing

What happens if I fail a backflow test?

If you fail a backflow test, your backflow tester will give you a report that shows which devices failed, why they failed, and how you can fix them. We advise following the next steps recommended by the specialist. The timeframe to repair a failed backflow prevention device varies from one municipality to another, but it’s usually 30 days. In Wisconsin, you have 10-30 days to fix a failed backflow preventer. After repair, the device must be tested again to ensure it works properly. All associated costs fall on the building proprietor.

How long does a cross-connection survey take?

The timing of a cross-connection survey can take anywhere from 1-4 hours. It depends on the size of the building and the complexity of its plumbing system.

How long does backflow testing take?

Backflow testing can take anywhere from 15 minutes to 3 hours, depending on how many devices are in your building.

Do I need both a cross-connection survey and backflow testing?

Cross-connection surveys and backflow testing have different purposes, and they are both required for maintaining a clean water supply. However, you don’t need to conduct them both at the same time. Cross-connection surveys are needed whenever you install or change your plumbing system, and backflow testing is often required annually.

What types of backflow devices require testing?

There are several backflow prevention devices that require testing: RPZ assemblies, DCVA devices, PVB (pressure vacuum breaker) assemblies, SVB (spill-resistant pressure vacuum breaker) devices, and RPDA (reduced pressure detector assembly) devices. There are some commonly used devices with a simpler design that don’t require testing, such as atmospheric vacuum breakers and dual check valves without test cocks.

How do I know if my facility is due for a cross-connection survey?

Common reasons to initiate a cross-connection survey include opening a new facility, renovating your plumbing system, changing your business type (from a bank to a restaurant, for example), or adding new water-using equipment like boilers.

Cross-Connection Control and Backflow Prevention Testing with J.F. Ahern

With an average of 16 years of experience in the field, Ahern’s plumbers are licensed and highly experienced in performing cross-connection surveys and backflow tests. We can identify potential issues early, helping to prevent damage and avoid costly repairs. Contact us today to schedule your next cross-control survey and backflow test.