I'm not sure i understand your question. If you mean where the water comes from it comes from an overflow box on your tank, if you mean the Euro-Reef, it comes w/ everything you need, just plunk it in the sump and plug it in (follow the directions though so you don't break it).
Sump basically works like this:
Overflow box, pvc pipe into the sump, return pump, pvc pipe back up into the tank.
Make sure your return pump is rated LOWER than your overflow box, otherwise it will cause more water to be pumped up than can be returned to the sump.