well I don't think Capetown problem is really the "water". Water is everywhere. The real problem on Earth are people, governors and politics. On Mars there are none of them, so it should be a really cool place right now :) Joke aside, I think you are right, we should solve our problem on Earth before starting to think to colonize other places. Some people often think a fresh start is better than trying to fix old/broken things, they just don't know that problems will popup everywhere.