I also take 12.5 mg of HCTZ, Norvasc 5. mg, and 50 mg Atenenol, + Lisinopril, and potassium, to make sure all my levels in the blood are safe for about 2 1/2 years. I drink at least 32-40 ounces of water all day long. It's correct, the diuretic makes you release fluid, but it cleans you out and the fresh water helps to keep you hydrated. My doctor says I'm doing the correct thing. I might add, he takes lab tests every 6 months to monitor my kidneys.
I might add, this regimin may not be good if someone has to watch water intake due to heart failure. Please check with your own doctor.