The majority of labors start with contractions, and not with the spectacular breaking of waters. But of course, it can happen to you. Breaking waters is something you should be on the look out for as soon as you enter the third trimester. In the movies, breaking waters are an extraordinarily spectacular event, that involves a lot of fluid. Reality is often different. When your waters break, you are more likely to notice the flow of a little fluid like a tap that was not quite closed properly than a big gush. Many women (especially those who had weak bladder control or pregnancy incontinence) think that they peed themselves when their waters break.
When your labor starts with a rupture of membranes, the sensation is rather similar. You can tell the difference between peeing yourself or your waters breaking in several ways. First, amniotic fluid is clear and does not smell of anything, unlike urine. Second, you will keep on losing fluid when your waters have broken. Prolonged rupture of membranes increases your risk of infection, so if this happens to you before you start having regular contractions you still need to head for the hospital or call your midwife if you are having a homebirth. If you get contractions before your waters break, like most women do, they might be ruptured artificially with an amniohook, or break spontaneously during the course of labor. Some babies are even born with their bag of waters intact!