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Cross Connection

Cross-Connection Control Program

Wisconsin Administrative Code, Chapter NR 810.15 , requires every municipal water supplier to develop and implement a comprehensive cross connection control program for the elimination of all existing and potential cross connections as well as the prevention of future cross connections.

Madison Water Utility delivers safe, high-quality drinking water every day. Our Cross Connection Control (CCC) Program is designed to safeguard public health and continue to keep the water system free of contaminants and pollutants.

Inspections are performed on all commercial, industrial and residential buildings connected to the water supply in order to detect actual and potential cross connections and to make recommendations for the installation of backflow prevention methods or devices, wherever necessary. This action ensures that contaminated water cannot backflow into our clean, drinking water supply.

Inspections occur on varying frequencies based on the hazard level of a given facility. The current frequency is as follows:

  • Commercial (High Hazard) & Industrial 2 to 3 Year cycle

  • (Low Hazard) 6 to 8 Year cycle

  • Residential 15 to 20 Year cycle

Residential surveys are coordinated with our water meter replacement program. When a water meter is replaced, a residential CCC inspection will also be performed. Commercial, industrial and some multi-family residential meters are tested more frequently and are not coordinated with the CCC inspection cycle. 

What Is a Cross Connection Control Program?

A cross connection control program is a cooperative effort between a municipality, health officials, plumbing contractors, and property owners. The purpose is to establish and administer guidelines for the control of potential cross connections and ensure their enforcement so that the public drinking water supply is protected both in the city water mains and within buildings to the point of use.

What Is a Cross Connection?

A cross connection is an actual or potential connection between the public water supply system and a source of contamination or pollution. The most common cross connection is a garden hose, which is easily connected to the public water supply system and can be used to apply a variety of potentially dangerous substances including chemicals and fertilizer. Other common cross connections include boilers, pressure washers, toilets, pools, and lawn irrigation systems.

How Does Contamination Occur?

Water normally flows in one direction, from the public water system through a customer’s cold or hot water plumbing system, to a faucet or other plumbing fixture. Under certain conditions, water can flow in the reverse direction. This is known as backflow which may occur when either backsiphonage or backpressure is created in a water line. Back-siphonage creates a vacuum which may pull or siphon contaminants backwards into the drinking water supply while backpressure may force contaminant-laced water back into the building’s piping system.

Back-siphonage may occur when there is a drop in the supply pressure of the water distribution system. This can be caused by a water line break, water main repair, or during a rapid withdrawal of water from a fire hydrant (i.e. flushing or firefighting). Backpressure may be created when a source of pressure, such as a pump, a steam or hot water boiler, or elevated storage tank creates a pressure greater than that supplied from the water distribution system.

How Is Contamination Prevented?

Identifying cross connections is the first-step in preventing potential water contamination. An effective CCC program involves implementation of methods or devices that prevent the backflow of potentially compromised water into the building’s plumbing system once a hazard has been identified. An air gap is the most effective barrier. A variety of mechanical barriers including the hose connection vacuum breaker, reduced pressure zone backflow preventer, double check valve assembly or atmospheric vacuum breaker can also be installed to prevent backflow.

What is the Extent of a Residential Cross Connection Survey?

Residential inspections are generally limited to the area near the water meter which is typically located in the basement. Since the utility does not inspect the entire property to the last free-flowing tap, the inspection is less intrusive on the homeowner, less time-consuming, and more easily conducted when the water meter is replaced. In lieu of a more thorough inspection, the utility must provide educational materials to property owners a minimum of once every three years about safeguarding their homes from cross-connections.

Follow the links below for additional information on cross connection control:


To confirm the status of your property or to ask questions about the program, contact the DPW Supt. Adam Lechner at 920-583-6700,

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