How much water flows through your kidney in one day?

To answer this question you need to know the normal range of Glomerular FIltration Rate of kidney. The normal range is about 90 - 120 ml/min/1.73 m^2

Let say that the average is 100ml/min / 1.73 m^2 and the human has 1.73m^2 surface area. If you convert it into one day, then the calculation would be:

100 ml/min / 1.73 m^ 2 * 60 min/hour * 24 hour / day * 1.73m^2 = 144000 ml/day = 144 liters/day