By Dr. Mike Roussell for Shape.com
Q: I've been drinking bottled water lately, and I noticed that I go through 3 liters at work alone. Is this bad?
A: It is good that you are drinking ample water throughout the day. While you may think you are drinking a lot, you are nowhere near a level that is hazardous to your health.
There is no RDA (recommended daily allowance) for water consumption, but when there isn't enough data for the Institute of Medicine to determine an RDA, they will set what is called an Adequate Intake level or AI. For water for women, the AI is 2.2 liters, or about 74 ounces -- more than the eight 8-ounce glasses that I'm sure you have often heard experts spouting off that you should be drinking.
While both the AI and 8x8 recommendations are fine, neither is grounded in very solid science. In fact the AI for fluid intake is just based on the median fluid intake in America, and it was set at this level set to "prevent deleterious, primarily acute, effects of dehydration."
How much fluid you need to drink each day in order to be hydrated is very individualized due to differences in physiology and activity, as well as where you live and how hot it is. Use these three guideposts to figure out your daily needs.
1. Avoid Being Thirsty
Thirst is a great piece of biofeedback from your body -- don't ignore it. I always tell clients that if you are thirsty, then it is too late. Research dating back to the 60s shows that people underestimate the amount of fluid they need to rehydrate, so if you are thirsty have a little extra to drink.
2. Spread Your Water Intake Out And Never Be "Full" from Water
You know that old trick where you down H2O before a meal so that you don't eat so much? It doesn't work. Along those same lines you should never drink so much water that you feel physically full. This is overkill, and the full feeling is your body telling you so. Water toxicity occurs when large amounts are consumed in a short period of time. As long as you are spreading out your sips throughout the day, your kidneys should be able to handle and filter the water you are drinking.
3. Coffee Does Count
Despite its Internet lore, coffee and caffeine are not diuretics. If you have a vente black coffee, that counts, so don't force more fluids down to make up for the "dehydrating effects" of the java you just drank.