Battery problems with '92 Cadi DeVille

A couple weeks ago...I was driving home on a [very] rainy night and went through a puddle that was about half way up on the tires. The car died, and a friend and I pushed it home. My father is a pretty good mechanic, so he took out the air filter (which was soaked) and the battery. We got a new battery and finally got it to start. That was 2 days ago. I went to go somewhere tonight and the new battery is dead. Can anyone help me out? Please don't tell me that I need a new car, because well...I'll be dead.

You might have left something on in the car.LOL.If it wasnt doing that before then u could have left something on.Unless you got some big sound system in there with a amp.OR your altinator could be dead.Which isnt a big problem