There are a few ways to determine if your water has broken. First, smell the fluid. Amniotic fluid smells slightly sweet or like chlorine (similar to semen). Then, put on a clean pad. If the pad keeps getting wet, particularly when you change position, you have probably experienced SROM. Third, sometime close to term, request a amnicator from your careprovider. With an amnicator, you can run it along your panties, bed, floor, or wherever you believe fluid has leaked, and if it is amniotic fluid, it will turn a dark green or blue color.
If it is amniotic fluid, you will want to remember the acronym TACO. TACO stands for Time, Amount, Color, and Odor.