Your doctor or midwife will use one of two common tests to see if the fluid leaking is your water or not. One simply involves a vaginal exam. During the vaginal exam, the doctor, midwife or nurse will introduce a small piece of paper, called litmus paper. This paper reacts by changing color when it is exposed to amniotic fluid. If the paper doesn't react, your water is not broken.
The other test is to take a small sample of fluid and look at it under a microscope. When amniotic fluid is dry the pattern it makes on the microscope slide looks like a fern plant and is therefore called ferning. So if they see ferning, your water has broken.
If your water has not broken you will be sent home to await the start of labor. If your water has broken, what happens next is dependent upon the protocols of your doctor or midwife. Good luck!