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Newsletter Article - March 2023


Cross-Connection Control Surveys: The Need Exists!

Steve Fox – Cross-Connection Control Program Coordinator, SC DHEC


Cross-Connection Control… … remains a critical link in protecting public health by maintaining the quality of our drinking water. Cross-connections are an actual or a potential cross-connection between the public water supply and any source or system not intended for potable use. These cross-connections, under certain circumstances, could allow non-potable – including hazardous – substances to enter the public water supply. Examples of these substances include gases, liquids, solids, and any matter that could change the color, taste, and odor of the public water supply. Many cases have been documented where cross-connections have been responsible for the pollution or contamination of the public water supply, and facility distribution systems, which have resulted in the spread of illness. Public water systems (PWS) in South Carolina have the responsibility of preventing water from unapproved sources from entering the public water supply system. Simply stated, a cross-connection that is not controlled, protected, or eliminated may allow for potentially dangerous contaminants to backflow through that cross-connection into a public water system under the conditions of backpressure or backsiphonage. The South Carolina Dept. of Health & Environmental Control requires public water systems to develop and maintain a cross-connection control program.


While many Cross-Connection Control programs focus on assembly testing requirements and tracking, an effective program should also, at minimum, establish authority, address program administration and recordkeeping policies, and establish cross-connection control survey requirements. Cross-Connection Control Survey: The Basics For this article, we will focus on the survey component. Surveying must be periodically performed to evaluate the hazard potential (high vs. low) of private water customer’s premises to the public water system, and to then require and enforce cross-connection control practices to protect the public water system. There are two cross-connection control methods a water purveyor may employ to protect the public water system; containment and isolation. 

  • Containment (Premise Isolation) is the installation of an approved backflow preventeron the service line to a water customer’s premise, thereby “containing” any potentiallynon-potable water from within the premise, from entering the public water system.


  • Isolation (Internal/Fixture Protection) is “point of use” protection intended to controlcross-connections at internal connections and water outlets within a private watercustomer’s premise to protect both the private and the public water system. Althoughsmaller, readily accessible facilities with minimal piping may be relatively straightforwardto assess for cross-connection hazards, larger industrial/commercial type facilitiesconsisting of complex, concealed or extensive piping systems may pose a challenge to

  • a water purveyor in managing them within their cross-connection control program, particularly if isolation is the required cross-connection control method to be enforced for such a facility. 


Certain jurisdictions have varied regulations pertaining to the practice of containment and isolation. The water purveyor may have chosen to require containment, and subsequently leave the responsibility of internal fixture protection, or isolation, downstream of an existing containment assembly to the private water customer.


There are, however, other jurisdictions that do not recognize containment as an approved method to protect the public water system and isolation is the required cross-connection control method to protect the public water supply. Private water systems have other regulations as well to keep in mind such as Plumbing Code, OSHA 1910-141b, FDA, industry-specific guidelines, etc., requiring them to provide safe potable water that meets acceptable standards to employees and visitors. Some of these regulations may directly or indirectly support the need for performing protection at the isolation level, notwithstanding of what the public water system recognizes as an approved cross-connection control method (containment or isolation). The private water user must ultimately comply with both public water system and any industry required regulations or directives.


Conducting a cross-connection control survey requires an understanding of the public water system, industry regulations, guidance from a public water system’s cross-connection control ordinance and program, knowledgeable personnel to conduct a survey, and accumulating accurate distribution system information from the facility. Equally important is effective communications among the appropriate stakeholders involved. Local community or political factors may have an impact on how compliance is accomplished. The following are a few key points a public water system should consider regarding performance of a cross-connection control survey: 

  • Regulations and Codes: Before any survey work begins, there must be anunderstanding of state cross-connection control regulations, plumbing codes, and thelocal cross-connection control program’s policy. Is containment automatically required atall facilities, per regulations? Will the public water system allow for isolation protection?Do codes/regulations require that the public water system enforce isolation beyond containment?


  • Containment: No matter the type of facility, a cross-connection control survey orassessment always begins at the service connection, or water meter. All serviceconnections to the facility must be identified and evaluated to determine if they are in factcontained, and if the containment method represents an approvedinstallation/arrangement. It is very common to have more than one service connection toa facility where maintaining continuous operations is critical, such as a hospital. It may bebeneficial to obtain underground piping drawings representative of the city water supplyto assist with the containment assessment, particularly if there are storage tanks,underground interconnections, and if multiple city water supplies are present. Thefollowing are some key points for completing a containment assessment:

  • Identify and evaluate all city water service connections and auxiliary watersupplies to the property

  • Identify and evaluate fire protection systems, lawn irrigation systems, etc.,supplied directly by the public water system (i.e., chemical additives, auxiliary water supply)

  • Identify and evaluate all containment backflow prevention assemblies

  • Identify and evaluate any water storage tanks on site


Isolation: If containment has not been implemented or if existing containment issuspected to be inappropriate for the degree of hazard, and/or if regulations and codessupport it (e.g. military regulations), a comprehensive internal “point of use”, or isolationcross-connection control survey of the facility may need to be performed. A completeisolation survey requires that each and every cross-connection as well as all backflowprevention devices, methods or assemblies be identified and evaluated to determine (1)if it is appropriate for the degree of hazard and (2) if it represents an approved installationthat meets code and manufacturer requirements. The public water system may elect toperform the survey themselves, to rely on facility personnel, or a third party to conductthe survey. The goal of an isolation cross-connection control survey is to determine ifboth the private and public water systems are properly protected, and also to define thehazard level the facility represents to the public water supply. The following are essential steps to be included in an isolation survey:


  • Trace the existing potable water piping system from the meter to all terminal ends.

  • Perform a point of use survey in areas where piping is concealed

  • Inventory and evaluate all existing backflow prevention devices, methods and assemblies at all cross connections

  • Evaluate pipe labeling and make corrections as necessary

  • Create an itemized list of corrective action requirements


There may be cases where a complete isolation survey may not be feasible or practical for the public water system, in which case an internal facility distribution system “general site assessment” by the purveyor may be required. This general assessment should include a review of the physical characteristics of the building, a description of various piping systems, processes, and whether the facility has their own cross-connection control program or best management practices. The data collected as a result of this assessment may be evaluated to warrant further action (i.e., require containment, require an isolation survey at owner’s expense, request specific facility information, etc.). Ultimately the public water system must accept, approve and be responsible for information obtained as a result of an isolation survey or general site assessment. This would suggest that the surveyor must be a competent, experienced individual in cross-connection control. Internal potable water piping “as built” drawings, assembly test records, and interviews with key personnel at a minimum may facilitate the completion of an internal survey or assessment.

The Question of Compliance 

Once a containment or isolation survey has been completed, the public water system needs to determine the compliance status. Data collected during the survey or field assessment must be used to (1) appropriately categorize a facility as being high- or low-hazard, (2) determine if the facility has complied with the requirements of the public water system cross-connection control program, or (3) define what the facility must do in order to comply, if applicable. An effective cross-connection control program must clearly define what is required to achieve compliance. Furthermore, a formal notification process should be in place to adequately communicate the compliance status, to require corrective action and the steps required to achieve compliance, and to define responsibility for providing safe drinking water. For example, if containment is required for a facility, and containment has been successfully implemented, the public water system should send notice transferring responsibility for providing internal safe drinking water to the private water system. The public water system in this case should also state in writing that there may be uncontrolled cross-connections inside the facility that require protection, that all backflow prevention assemblies should be tested per plumbing code, and that piping systems should be labeled appropriately to maintain a safe potable water distribution system. Not only is this providing education and awareness, but it is potentially reducing liability for the public water system in the event a future internal facility backflow incident occurs. 

A Final Thought 

“If we do not look, we will not find. If we do not find, then we do not have an issue. If we do not have an issue, we do not see the need.” For this reason, many local officials do not see a need. Surveying is an important part of any Cross-Connection Control Program and will assist in demonstrating the need.

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