Al's right, in Houston all bets are off with flooding esp during tropical storms.
I always find this website useful for folks wanting to see the flood zones : http://www.harriscountyfemt.org/
I have always found that surrounding home owners are usually happy to tell you all about their neighborhood and if there are drainage problems.
Your insurance agent will always tell you that even if you are not required to have flood insurance, it is worth its weight in gold if it does flood since standard insurance will not cover rising water .
Good luck in your home search !