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Cross Connection Control
Cross Connection Control
Backflow and Water System Contamination
Water distribution systems are designed to operate with continuous positive pressure. This helps ensure contamination cannot enter the system through points of connection or leaks. Though difficult to detect, water pressure can sometimes be disrupted causing water to accidentally flow backwards. This can result in siphoning of unknown materials into the drinking water. Other times, pumps or water heating devices in homes and businesses can overcome the water system pressure. These are examples of backflow, and contamination during a backflow incident can occur through the plumbing and points of use. These backflow events have resulted in documented contamination in water systems across the country, but most cases of backflow are left undetected.
Cross Connection Prevention In Michigan
A cross connection is an unprotected plumbing arrangement through which backflow can occur. To identify and prevent cross connections in community water supplies, Part 14 of the Michigan Safe Drinking Water Act Administrative Rules (SDWA) prohibits cross connections and requires each water supply to implement a cross connection prevention program including inspections, testing, recordkeeping, and education. The Michigan Department of Environment, Great Lakes, and Energy (EGLE) oversees public water supply programs to identify and prevent cross connections throughout Michigan.
In order to protect public health from the risk of backflow, the SDWA works together with the Michigan Plumbing Code requirements to control cross connections. A common way to control a cross connection is to install a backflow preventer. The basic function of a backflow preventer is to stop water from flowing backwards. There are many types of backflow preventers, and it is important to match the chosen backflow prevention method with the specific situation. A local water system cross connection inspector should have the specialized training necessary to identify cross connections and determine what level of protection is needed.
Testing of Backflow Preventers
Some types of backflow preventers require periodic testing at some frequency to ensure they are functioning properly. As with any mechanical device, backflow preventers have been shown to fail. Failure rates of protective devices can be substantial in some communities and vary based on several factors. If a water customer has a cross connection protected by a testable backflow preventer, they may expect a letter from the water system periodically requesting it to be tested by a professional tester with ASSE 5110 certification. The cost of installation and testing is often paid by the water customer. However, the benefit of a functioning backflow preventer is the protection of health of those in proximity to it, as well as other water customers in the area (i.e. neighbors). An excellent resource is the American Society of Sanitary Engineers (ASSE) website, linked below, for certified products, certified tester lists, and training opportunities to become a certified tester.
Inspection of Water Customers for Cross Connections
In addition to requiring testing of backflow preventers, water systems are also required to conduct onsite inspections of all water accounts at some frequency to assess the risks from cross connections. These inspections will typically be noticed in advance and will be conducted with a reasonable expectation of privacy (particularly in the case of a residence). Inspections are crucial to identify the risks inherent to existing plumbing systems that are not constructed to modern day standards to protect from backflow. The water system is required by the State to maintain the legal authority to conduct inspections, and inspectors must be trained to identify cross connections and require corrective measures to protect public health.
Public water supplies are required to implement a cross connection prevention program in all customer types. The water supplies’ primary focus may be on high hazard water customers, which present a greater risk of contaminating the water system. However, even a residential home has risks of contamination during a backflow incident (irrigation, sinks, toilets, hose bibs, etc.). Modern plumbing regulations often help prevent these situations, but many homes have older plumbing or DIY projects that may result in unprotected cross connections and pose a risk. EGLE requires water systems to develop a program for inspection, testing, and education of all customer types, including residential customers.
Many water systems struggle with staffing levels and expertise to adequately comply with the Michigan requirements for a cross connection program. It is acceptable to engage the services of a private contractor specializing in cross connections to help with program implementation, and many companies are available for this service. However, it is important to remember the water system is ultimately responsible for maintaining compliance with the Safe Drinking Water Act and administrative rules.
References and Resources
EGLE is continually assessing the current status of cross connection prevention in the State of Michigan. This includes review of the regulations, self-auditing of compliance procedures at EGLE, and collaboration with partners in the industry. A report was recently completed in conjunction with the Graham Sustainability Institute and the University of Michigan.
To learn more about cross connection control, please consider attending EGLE’s on-demand training, or sign up for upcoming cross connection training through EGLE, MI-AWWA, or MRWA.
If you have concerns about your water or cross connections, EGLE encourages you to submit those via our Drinking Water Concern System.
If you have an environmental or drinking water emergency, please contact our PEAS hotline 24/7 at 1-800-972-4706.