Example of Reversal of Flow – Backflow Backsiphonage Case 6

As seen in this illustration there is a submerged inlet in the second floor bathroom and a car hits a fire hydrant in the vicinity of the home. This causes the water to flow out of the fire hydrant, which creates negative pressure within the distribution system. The negative or sub-atmospheric pressure caused by the rush of water from the fire hydrant pulls or siphons the water out of the bathtub through the submerged inlet.  Individuals consuming water at the time of the incident consumed bathtub water.

The hot and cold water faucets to the bathtub should be installed with the proper air gap separation.