Backflow and Cross Connection Prevention

What is a Cross-Connection?
A cross-connection is an actual or potential connection between the safe drinking water (potable) supply and a source of contamination or pollution.  State plumbing codes require approved backflow prevention methods to be installed at every point of potable water connection and use.  Cross-connections must be properly protected or eliminated.

How does a contamination occur?
When you turn on your faucet, you expect the water to be as safe as when it left the treatment plant.  However, certain hydraulic conditions left unprotected within your plumbing system may allow hazardous substances to contaminate your own drinking water or even the public water supply.

Water normally flows in one direction.  However, under certain conditions, water can actually flow backwards; this is known as Backflow.  There are two situations that can cause water to flow backward: backsiphonage and backpressure. 

May occur due to a loss of pressure in the municipal water system during a fire fighting emergency, a water main break, or system repair.  This creates a siphon in your plumbing system, which can draw water out of a sink or bucket and back into your water or the public water system.

May be created when a source of pressure (such as a boiler) creates a pressure greater than the pressure supplied from the public water system.  This may cause contaminated water to be pushed into your plubming system through an unprotected cross-connection.

Additional Information: