Water is vital for physiological functions and thirst signals the body's need to replace lost water through processes like sweating. Most people need around 8 glasses of water daily but more in hot weather or after heavy sweating. Polydipsia is excessive thirst and causes people to drink too much water, which can lead to electrolyte imbalances. Nocturia is waking at night to urinate, caused by producing too much urine, low bladder capacity, or a combination of the two. Polyuria is excessive urine production of over 2.5 liters per day, which can indicate bladder, urinary tract, or metabolic issues like diabetes.