I have also seen the underground conduits full of water and I have always wondered about installing a "T" into the conduit with the vertical leg left open and pointing down do allow water to drain. I was told that this will also allow any possible ground water to flow in, but it still seems to make sense to me to give the water someplace to drain. I was even going to fill the hole under the "T" with rocks to provide a better escape. I think allowing the water to drain away and risk the water flowing in is better than letting the electrical circuit sit in water for all eternity, but I am curious what a professional Electrician would say to this since I am only an amateur sparktrician.