Although the spraying of urine is usually associated with male cats that are marking their territory, female cats can actually spray too. While their urine doesn't have the same strong odor as that of an unneutered tomcat, it's still smelly and destructive. If your female cat is spraying urine inside your home, you'll need to take some steps to stop this damaging behavior.
Take your cat to the veterinarian for a thorough exam. Inappropriate elimination behaviors such as spraying can indicate a medical problem such as an infection. Physical causes should be ruled out before you address the problem from a behavioral standpoint.
Have the cat spayed if this has not been done already. Unspayed female cats are much more likely to spray urine than those who have been "fixed." Spaying also reduces the chance of certain medication conditions such as breast cancer.
Clean the cat's litterbox daily. Cats are very clean animals, and when their litterbox is dirty it increases the chances of inappropriate elimination. If you have more than one cat, you should also have multiple litterboxes. A good rule to follow is at least one box per cat.
Spray a repellent in the areas that your female cat likes to mark. You can find an appropriate repellent product in your local pet store. Use the spray in all the spots where you've noticed your female cat spraying.
Get Feliway spray or plug-ins to calm the cat and reduce her anxiety if she's feeling territorial. Spraying is a way of marking territory, and this can be especially common if you have multiple pets. Feliway contains a calming pheromone that relaxes the cat and reduces her need to spray.
Shoot the cat with a water gun when you see her spraying. The water is harmless, but it will deter her from the behavior--she won't link the punishment directly to you and become afraid of you.