DandV

Only if you make the assumption that the electric bilge pump does indeed have a float switch for automatic operation. Perhaps on this boat, it is just an electric improvement to a manual semi rotary bilge pump?

Fire sprinkler systems are normally fabricated from "black" steel pipe and remain water flooded without problems for decades. Any oxygen is quickly depleted from the initial charges of water and internal corrosion then stops. System monitoring for any pressure loss, minimises requirements for ny make-up water, with its attendent dissolved oxygen. But if you ever drain such a system down, the water certainly is not pristine, varying any where from bright orange, in newish systems, to near black in old systems. As smart alecs have discovered after triggering such systems by breaking the sprinkler glass bulbs.