Did you know when your water broke?

My first pergnancy I had no idea my water broke. The hospital sent me home when I was 4 1/2 cm because i wasn't in enough pain at 40 weeks and 4 days. Well tha pain came on and I went to use the bathroom (my water broke while I was peeing) but I had no idea until I went to the hospital and they said my water was already broken...so I'm nervous the same thing will happen with baby number 2. Anyone else have something like this happen? How can you tell the difference?