What causes excessive drinking in cats?

There are several conditions that can result in excessive drinking in cats. The most common causes are diabetes, kidney disease and an overactive thyroid (hyperthyrdoidism). A cat normally drinks 50ml water/kg bodyweight per day. To find out if  your cat drinks excessively you need to measure its daily water intake. It is abnormal if your cat drinks more than 100ml of water per kg/body weight per day. If this is the case you should consult a veterinarian.