I know this thread is a couple of days old now, but I'm curious: Those who had trouble getting formula or water through security-was it separate from your carry-on and did you declare it? I ask because I've flown 4 times (DTW and MCO) in the last couple of months (last being a couple of days ago) and never was my bottles with water in them to mix formula even given a second glance. I had it in a separate case, handed it to them and told them it was for the baby. That was it. They did one time yell "baby supplies coming through!"
They did, however, dig through my backpack for several minutes with a flashlight in Detroit. I asked "did I put something in there I shouldn't have?" and the guy just smiled and said "I don't think so", so I have no idea what that was about.