Hello doctor, i just wanted to know what should be the minimum consumption of water in 1 day for a grown up? thanks in advance.

About 1.2L: Obligatory urine losses are about 1/2 cc/kg/hr. So that an avg 70 kg individual would have to consume about 720 cc/day just to make urine. Because of losses through the skin and lungs and adding a bit of fluid fo cushion, the minimum fluid requirement is on the order of 1.2 l/day. Some of that fluid may be obtained from your food.

Enough to pee: There is fluid value in many items that people consume.In theory, you could just get the fluid value in these foods (apple sauce=95% water) & do fine. You need to take in enough "fluid value" to keep a normal fluid balance in your body.This is evident when you eliminate the material in your urine. If you pee every 8 hrs you have likely taken in enough.