Many things could be causing a female dog to leak urine.
Medical conditions that cause your dog to drink more water than normal could cause overflow incontinence or your dog could be suffering from bladder infections, Urinary Tract Infections, Kidney Disease or a host of other conditions.
A female or even male dog with Cushing's disease can cause a dog to have a weak bladder which can lead to the dog leaking urine.
I'd recommend taking the dog to the vet if possible to have her checked out and find out what's exactly wrong with her.
In some cases the female dog leaking urine can be cured but for now you can buy diapers for dogs that have a tail hole cut into them which will prevent the dog leaking urine on your floor.