Buy an extra water pump,  leave it in the box and put it in the cabinet with your exisiting pump.   I was lucky I tried to dewinterize the trailer about 2 days before a trip and realized the pump would build no preasure.  Had the spare one installed in about 30 minutes,  easy job,  just a little uncomfortable.  I could have never ordered a pump and had it delivered in time for the trip.  I just went online and bought another spare to put back in the cabinet.

IMHO