Flojet R3426-500 Water Pump

BLT

In common with many caravans these days, ours is fitted with an inboard diaphragm water pump.  Previous caravans used the external submersible type, which was relatively inexpensive to replace and required no fitting, so carrying a spare was not a problem.
 However, do I need to go to the expense of purchasing a complete unit in case of failure, or are there specific parts or kits available to carry "just in case".  I wouldn't risk foreign touring without some sort of back up in the event of a problem.   Would
appreciate advice please.         

Brian