We are always banging on at our patients to drink more water and suggesting the right amounts that they should be drinking.  They rightly ask how much and we tell them.

 

This is the score:

 

You lose:

 

Normal Weather        Warm Weather          Warm Weather

No exercise                No exercise                Exercise

 

Skin (not sweat)       350 ml                          350 ml                          350 ml

Sweat                        100 ml                          1400 ml                        5000 ml

Respiratory Tract    250 ml                          350 ml                          650 ml

Urine                         1400 ml                        1200 ml                        500 ml

Faeces                       100 ml                          100 ml                          100 ml

 

Total                          2,300 ml (2.3l)             3,300 ml (3.3l)/            6,600 ml (6.6l)

 

So, a fair bit every day. 

 

Now you do get water from your food and from metabolic water production (Google it), typically about 1.5L, so we suggest:

 

Sedentary individuals drink at least 2L or about 8 cups of water per day

 

Athletes in normal climates drink at least 3L or about 12 cups of water per day.

 

Athletes in hot weather climates drink at least 4L or about 16 cups of water per day.