What happens when you pour a gel with water instead of TAE?

"I primarily did undergrad research in computational biology, so my first rotation in grad school was my first time doing "wet" molecular biology that wasn't for a lab course. I think I spent 1 1/2 weeks making gels with water. During that span of time, I asked a bunch of people what I was doing wrong and I got the usual advice to change the concentration of various things. Finally, a postdoc figured it out. The rest of my "wet lab" experiments went OK during that rotation!"