Dear Dietitian: How much water do we need?

Leanne McCrate

Dear Dietitian,

I have been eating healthier and drinking more water. I’ve heard that we need 8 glasses of water a day, but I don’t enjoy plain water, and I have a hard time getting that much in. Do you have any suggestions?



Dear Laura,

Good for you for your health change! The answer to how much water we need each day is not exact because it varies according to age, weight, and activity level. The good news is there is more than one way to meet your fluid needs.

Many people use fresh lemon or lime to flavor their water. There are commercial flavors sold in the grocery store than can zest up your drink. You may also use calorie-free or low-calorie, decaffeinated beverage to meet part of your water requirements.

Water is something many of us take for granted, yet we cannot live without. It is tasteless, colorless, odorless, contains no calories and few trace minerals, yet we must have it. If one goes without food, the body can sustain for about three weeks. Without water, depending upon the circumstances, humans can only survive one to seven days. Our bodies are made up of 60 percent water, and every cell needs it to function.

The human body needs water for several functions: to regulate body temperature, to protect organs and tissues as well as lubricate joints, to aid in digestion and help prevent constipation, and to dissolve nutrients and carry them to the cells.

To stay healthy, humans must maintain water balance, which means that water losses must be made up for by water intake. We get water from food and drink and lose it as sweat and urine (a small amount is also present in feces). We also lose water when we exhale.

Under certain circumstances, we need more water. In extreme heat or strenuous exercise, we sweat more and the body works harder to maintain a healthy temperature. These functions require more water. It is possible to drink too much water (water intoxication), but it’s not likely unless there is an underlying medical condition such as kidney problems. If you think you are at risk for water intoxication, talk to your doctor.

Finally, how much water do we need? The general recommendation is to let thirst be your guide and know the signs of dehydration – confusion, mood changes, or urine that is darker than usual. The Mayo Clinic recommends drinking one glass of water with each meal and between each meal. Remember that decaffeinated, calorie-free or low- calorie beverages are allowed to meet some of your water needs.


Dear Dietitian

Leanne McCrate, RD, LD, CNSC is a Registered Dietitian, Licensed Dietitian, and Certified Nutrition Support Clinician from St. Louis, Mo.