It has been my experience that if the city water pressure is less than the pump PSI, the pump will run and draw water from the fresh water tank. Before I bought a "better" pressure regulator, we found that we had more shower pressure with the pump. Then, I upgraded to the higher flow unit and the pump doesn't run even if it is turned on.
Based on that, I ass-u-me the better city water pressure overrides the pump.
Life is a journey, not a destination.
2005 Georgetown 359ts
Bill & Virginia, Kentucky
Nights camped in 2011...78 , 2012...73,
Nights camped in 2013...123, 2014 ...101