I'm building a simple plant watering station, which uses a relay-controlled submersible water pump (this one). The intent is to submerge the pump into a large enough water container to avoid frequent refills, but this means that the point where the pump's relatively short wires are extended will be submerged as well.
So here's the question: what is the correct way to insulate such joints? I'm currently using shrink tubing but I doubt it seals it well. Is there a better way?