How much water should I drink a day?
To answer this question, you need to know three facts.
- Bladder volume – the human bladder volume is 300 (200-400) mls – i.e. quite small – a can of coke
- Frequency of urination – the average adult urinates approximately 6-7 times a day, depending on fluid intake
- Urine output – this will lead to a urine output of say 6.5 x 300 mls = about 2L (well 1950 mls!), based on drinking about 2.5L a day (500 mls insensible loss).
OK OK. So how much water should you drink?
Answer. There is no normal (or desired) fluid intake. But about 2.5L is fine. That can equate to 8 x 300 ml glasses of water a day. But that water does not have to be pure water. It can be water in tea, coffee, mild, squash, fruit, fizzy drinks. The odd beer is fine too.
If you drink more than that, you will urinate more times a day.
If you have kidney problems, do you need to drink alot to ‘flush the kidneys’?
There is no evidence for this. Drink if you are thirsty, not if not.
Duration of urination
Interestingly, mammals empty their bladders on average for 21 seconds (standard deviation 13 seconds), despite a difference in bladder volume from 0.15 ml (mouse bladder) and 300 ml (human) to 18 L (elephant) and 300 L (blue whale).
[Why don’t you time yours?! MyHSN Ed.]
