Do You Really Need Eight Glasses of Water a Day?

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May 05, 2004 | 34,912 views

By Dr. Joseph Mercola
     with Rachael Droege

How many of you have heard that we are dehydrated and need to drink at least eight eight-ounce glasses of water a day? I know that is what I have traditionally been exposed to. I used to advise that people follow an even more refined rule of thumb--for every 50 pounds of body weight you carry, drink one quart of spring or filtered water per day. This would increase daily water intake to 12 to 16 glasses for most of us.

However, after awhile I began to question this and I further refined my recommendations to use the color of your urine as a guide to how much water you should be drinking. As long as you are not taking riboflavin (vitamin B2), which fluoresces and turns your urine bright yellow (it is also in most multi-vitamins), then your urine should be a very light-colored yellow. If it is a deep yellow then you are likely not drinking enough water.

So I was delighted to read in my Family Practice Newspaper that an Institute of Medicine Panel actually reached the same rational conclusion. They rejected the conventional wisdom that people need to drink eight glasses of water a day and concluded that on a daily basis people get enough water from normal drinking behavior, such as drinking beverages at meals and in other social situations, and by letting their thirst guide them.

This is not to say that getting enough water isn’t important. We can exist without food for months, but without water we can only survive for a few days. Your body is made up mostly of water, which:

Every day you lose water from the body through urine and sweat, and this fluid needs to be replenished. However, your body has come equipped with a mechanism that tells you when you need to replenish your supply--it’s called thirst!

Let Your Thirst be Your Guide

When your body begins to lose from 1 percent to 2 percent of its total water, your thirst mechanism lets you know that it’s time to drink some water. If you are healthy, then drinking whenever you feel thirsty should be an adequate guide of how much water you need. You can confirm whether you are drinking enough water by looking at the color of your urine, as mentioned above.

Of course, if it’s hot outside or you are engaged in exercise or other vigorous activity, you will require more water than normal so be sure to stay well hydrated in these cases. Additionally, as we grow older our thirst mechanism works less efficiently so older adults will want to be sure to drink water regularly, and again make sure their urine is a light, pale color.

Don’t Overlook Water Quality

Perhaps the question we should have been asking for so long is not how much water should we be drinking, but what type of water should we be drinking? The answer is clean, spring water and filtered water--I do not recommend drinking tap water or distilled water. Contrary to the traditional belief, it’s also important to avoid fluoridated water.

One of the most important steps you should take for your own health and the health of your family is to ensure the safety of your tap water supply. This will help you to determine what type of filter you need to make sure your water is free from heavy metals, bacteria and other harmful contaminants.

The reason why filtering your own water is so important is because you really want to avoid bottled water unless it is absolutely necessary as it is a huge strain on the environment. Plus, some bottled water may not be any cleaner than tap water. On a side note, remember to avoid storing your water in typical Nalgene bottles as they can leach an unsafe chemical called BPA into your water. I recently switched to the high-density polyethelene (HDPE) Nalgene bottles, which appear to be safer, to store my water when I go on trips and cannot use a glass bottle.

If you are interested in reading more about this topic, then you will want to review this 500-page report from the National Academic Press, which includes a comprehensive discussion of water and human health.

Related Articles:

The Absurdities of Water Fluoridation

Why I Now Say No to Distilled Water Only

Warning! That Glass of Drinking Water Is Recycled

Another Reason Why Women Can Retain Water Explains Why Too Much Water Can Harm Marathon Runners

More Than 50% of Children Drinking Fluoridated Water Have Fluorosis

Coke Wants to Fool You With Their Bottled Water