To truly go without water you would also have to go without food.
After about 3 days you will begin to suffer serious dehydration, tiredness, headaches and confusion, alonmg with vomiting and elevanted heartrate. After 5-7 days you will suffer from hallucinations, broken skin, lesions, increased vomiting and the inability to absorb water even if you had any due to changes in your body chemistry.
A lot depends on the ambient conditions, your general build, health and age.
The answer is you can survive for between 12 hours and 12 days without water depending upon those conditions.