Example of Reversal of Flow – Backflow Backpressure Case 2

Sewage seeping for a residential cesspool pollutes the private well which is used for lawn irrigation. The internal domestic water system is connected to  the public water system and the well supply they are separated by a valve. The purpose of the connection is to prime the well supply for emergency domestic use. The well water is primarily used for lawn irrigation.

The well pump pressure is greater than the public water system pressure. Since the well pressure is greater than the public water system pressure, during periods of low public water system pressure well water is pumped into the public water system through the open or leaking valve.

The connection between the two systems shall be separated.