Sure Water Fast will cure Pelvic Floor Muscle tightness. It may take long fast to cure this depending on what other ailments your body needs to clear up.
There are a few things you can do before starting a fast. Following steps should release the tension.
1. Take Epsom Salt bath twice a day for at least 40 minutes. Make sure your lower body is under water the whole 40 minutes.
2. Take Magnesium 400mg twice a day.
3. Do a Butterfly Yoga pose twice a day for 10 minutes.
4. Use warm bottle compress on your pelvis and between two legs (between anus and genitals)
5. Depending on your gender you may benefit from PT.