How do you quench your thirst?

For as long as I remember, I am constantly thirsty. I know that you are suppose to quench thirst by drinking a lot of water and that does not work for me. I can drink a gallon of water and still be thirsty. I am not diabetic and yes I have been tested I am hypoglycemic but the doctors said that it should not affect my thirst. What should I do? I can't keep drinking like I do.