How Much Water Should I Drink in a Day?

Water is more important to our bodies than anything else. It lubricates out joints, keeps our blood flowing, helps our organs work. How much water do we really need in a day?

While conventional wisdom holds that you need eight glasses of water per day, this is not the case for every individual. In reality, a number of factors influence how much water each person requires, and water needs can change depending on circumstances. To make sure you stay hydrated and healthy, it is important for you to know why you need water, how to tell when you are not getting enough and how much water the average healthy person needs per day.

The Importance of Getting Enough Water

Every cell in your body needs water to function. Water helps your body remain at the correct temperature, flushes out wastes, carries essential nutrients to your cells, keeps the tissues in your nose and throat moist, helps prevent constipation and kidney stones and performs other essential functions.

If you lose more water than you take in, you can rapidly become dehydrated. When this happens, your body no longer has the ability to carry out essential functions. Mild dehydration can make you feel tired, sluggish and dull. In severe cases, your body may not be able to get sufficient blood to your organs, so dehydration becomes a life-threatening emergency.

Factors Affecting How Much Water You Need

The amount of water you need to drink each day depends on the amount you lose, and this varies depending on your age, weight, health, activity level, the current climate conditions and other factors. While everyone loses some water each day through breathing, urination, sweating and bowel movements, some individuals lose more water than others.

Individuals who may need to drink more water than average include the following:

  • Women who are pregnant or breastfeeding
  • People who live in dry climates
  • Individuals who live in hot climates
  • Those who are physically active
  • People with diarrhea
  • Those on certain medications
  • People with illnesses, like bladder infections, that produce increased urination
  • People with fevers

How to Tell if You Are Drinking Enough Water

The best way to tell if you need more water is to look at your urine. If you are drinking enough water, your urine will be clear or faintly yellow. If your urine is a moderate to dark yellow colour, it is likely that you are not getting sufficient water.

You should not wait until you have a dry mouth or feel thirsty before you take a drink. By the time you notice these symptoms, you may already be mildly dehydrated.

Expert Recommendations

The Institute of Medicine recommends a total of 125 ounces, approximately 3.5 litres, of water per day for the average healthy man and 91 ounces, about 2.1 litres, per day for the average healthy woman. This recommended amount includes water from all beverages and from solid food. For the average person, about 80 percent of this water typically comes from non-alcoholic liquids and 20 percent from food.

While you do not need to consume your entire daily water requirement in the form of straight water, the experts at the Mayo Clinic say that the old advice to drink eight glasses of water and other beverages per day is a good rule of thumb. They advise drinking eight servings of fluid, including water, each day. Each serving should total 8 ounces, approximately 0.2 litres.