Connections & Contaminations

A cross-connection is a direct or potential connection between any part of the public water supply system and a source of contamination or pollution. The most common form of 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 dishwashers, toilets, pressure washers, boilers, pools, and lawn sprinkler systems.

Cross-connection control program questions can be directed to the City of Hartford Water Utility at 262-670-3710 or Hydro Designs Inc. at 800-690-6651, option 1.

How Contamination Occurs

Water normally flows in 1 direction, from the public water system through the customer's cold or hot water plumbing to a sink connection or other plumbing fixture.

Under certain conditions water can flow in the reverse direction. This is known as backflow. Backflow occurs when a back siphonage or backpressure condition is created in a water line.

Definition & Classification

  • Back siphonage may occur due to a loss of pressure in the water distribution system during a high withdrawal of water for fire protection, a water main or plumbing system break, or a shutdown of water main or plumbing system for repair. A reduction of pressure below atmospheric pressure creates a vacuum in the piping. If a hose bibb was open and the hose was submerged in a wading pool during these conditions, the non-potable water in the pool would be siphoned into the house's plumbing and back into the potable water supply.
  • Backpressure may be created when a source of pressure, such as a pump, creates a pressure greater than that supplied form the distribution system. If a pump supplied from a non-potable source, such as a landscape pond, were accidentally connected to the plumbing system, the non-potable water could be pumped into the potable water supply.