Hydration: How Much Water Is Enough?
The Importance Of Water
You know that going more than a few days without enough to drink can be fatal. Do you know why? We have trillions of cells in our bodies in each of which millions of chemical reactions are taking place. Most of these reactions are facilitated by the actions of hydrogen (H) and hydroxide (OH) ions. Water (H2O = H+OH) is a prime source of these ions. If there isn’t enough water to provide them, the chemical reactions don’t occur and the cells begin to die.Thinking about this on a higher level, water is essential for most of our body fluids, including blood, tears, cerebral spinal fluid and the fluid in our joints. If we are not sufficiently hydrated, we also don’t make enough of these protective fluids.How Much Is Not Enough?
With respect to fluid intake, our goal is to avoid dehydration. So, how do you know if you’re dehydrated? Here is a list of some signs and symptoms†:Mild to moderate dehydration:
Severe dehydration (treat as a medical emergency):
Gauging How Much You Need
Other ways of calculating water intake are based on body weight. For example, the idea that half your weight in pounds equals the number of ounces you should drink. This means a person who weighs 130 pounds should drink 65 ounces – or about 8 glasses that are 8 ounces each (which ties into the 8 glasses a day rule of thumb).
Some practitioners suggest using the colour of your urine as a gauge. If you’re well hydrated, your urine should be pale yellow (think “banana”) before it hits the water in the toilet. If you’re not well hydrated, your urine will be darker (think “lemon”, or worse, “orange”). Others recommend being guided by thirst.
None of these methods is perfect. Age and stage of life have a big impact on the amount of water needed as well as perceptions of thirst. For example, children and the elderly are less likely to experience thirst even when they are dehydrated, and pregnant women may need to drink more as their weights (and blood volumes) increase during their pregnancies.
Also, the thirst and urine colour methods evaluate water intake after the fact – that’s not too helpful if your goal is to prevent dehydration.
My suggestion is that people combine methods to estimate how much water they need. Start by using the weight calculation to determine an estimate of what you should drink on an average day. Increase your intake if you’ve been perspiring or drinking “dehydrating” fluids that contain caffeine or alcohol. Make a quick check of the colour of your urine before you flush and adjust your intake accordingly. Lastly, if your mouth feels dry, drink some water.