How Much Water Do I Need?

By Tracey A Planinz, PhD

This is one of those questions where many experts have a difficult time coming to an agreement over the answer.We have all heard the rule, “8 – 8 oz. glasses of water each day”, also known as the 8 x 8 rule.

According to the Mayo Clinic, doctors generally recommend 8 or 9 cups, a total of 72 ounces, per day. But, is this really enough or appropriate for everyone? The truth is there is no one-size-fits-all rule when it comes to water consumption. There are several factors which determine how much water you will need each day.

Water used by the body

Water ConsumptionThe body uses water to help regulate body temperature and aid in metabolic processes.

It also helps flush waste from the body and is used to assimilate many vital nutrients. 90 percent of our blood is water, and our body as a whole is about two-thirds water.

As water is spent by the body, waste is excreted by the kidneys, and through perspiration.

Men verses women

Because men and women generally differ in both size and metabolic activity, men typically need more water than women on a daily basis.

The National Institutes of Health recommends men drink at least 3 liters or 13 cups of water each day.

Women require less at 9 cups, or a little more than 2 liters daily. Women also require nearly one and a half times the minimum amount when breastfeeding.

Activity level

Your body will spend a minimum of 6.3 cups just to maintain normal function and temperature. It is lost through breath, sweat and urine. Another 4 cups will be lost through the excretory system.

However, the more activity you participate in, the more water is used and then lost by the body. Of note, although your activity level is decreased during times of illness, you should actually consume even more water to prevent dehydration and help the healing process.

How much do I need?

A better rule of thumb is one that is supported by many natural health professionals, and is customizable to each individual. That is, you should consume at least half your body weight in ounces each day.

For example, a 120 lbs. female requires roughly 60 ounces of water, or about 3 sport bottles worth daily. A 190 lbs. man would need at least 80 oz. of water each day.

As activity levels increase, so should the amount of water consumed. It is important to calculate your own minimum daily requirements and find ways to incorporate more water into your daily routine.


Other factors which may influence water intake include age, weight and medications which may cause dehydration. Caffeinated drinks such as coffee, tea and soda can also be dehydrating.

The most important thing to consider is to pay attention to your body’s signals. If you feel thirsty, drink water.

If you experience any signs of dehydration, such as dizziness or headaches, increase your water intake. Avoid non-hydrating drinks like alcohol and coffee as much as possible, especially during warmer weather. If you experience severe dehydration or heat stroke, seek medical attention.


1. Mayo Clinic: Nutrition and Healthy Eating: Water –

2. National Institutes of Health: Medline Plus: Water in the diet -