Example of Reversal of Flow – Backflow Backpressure Case 3

A valve connection exists between the potable and the non-potable water system aboard the ship. The non-potable water system is equipped with a high pressure pump which is capable of overcoming the public water system pressure.

While the ship is connected to the public water system for the purpose of taking on water for the ship ‘s potable water system, the valve between the potable and non-potable water system is left opened. While the ship was taking on water the fire pump was tested. Since the pump pressure was greater than the public water system pressure non-potable water is pumped into the public water system distribution system.

A backflow prevention device shall be installed on the public water system service line to the ships pier. Also, backflow prevention device shall be installed within the ships potable water system to prevent cross-connection incidents on the ship.