Power off/ failure to trigger NO state on resumption
The circuit below would do that for you.  When power is on, the pump would start immediately.  Press the button to shut it off by holding the relay energized.  The next time power goes out the relay will return to the de-energized state and when power returns, the pump would automatically come on again.  

Note that the relay would be drawing power constantly when there is power, when the pump is off, so it may not be the most efficient way to do it.  Make sure the relay coil and button are rated for the supply voltage and the relay contacts are rated for the pump current.







simulate this circuit &ndash; Schematic created using CircuitLab