Are you drinking enough water each day? For many people, the answer to this question may be no. When we aren’t getting our personal water intake needs met, there can be negative impacts that follow. As noted by the CDC and Harvard Health Publishing, water helps keep our bodies functioning properly in a wide variety of ways: 

• Keep a normal temperature 
• Lubricate and cushion joints 
• Protect your spinal cord and other sensitive tissues 
• Get rid of wastes through urination, perspiration, and bowel movements 
• Avoid dehydration 
• Carrying nutrients and oxygen to your cells 
• Flushing bacteria from your bladder 
• Aiding digestion 
• Preventing constipation 
• Normalizing blood pressure 
• Maintaining electrolyte (sodium) balance
• And more! 

So how much water should we be taking in? As Harvard Health Publishing states, “The daily four-to-six cup rule is for generally healthy people” – so it’s just a general rule. And while some people drink too little water, it’s also possible to drink too much, especially if you have certain health conditions such as thyroid disease or kidney, liver, or heart problems.

As it turns out, when it comes to how much water a person should be drinking each day, there’s no one-size-fits-all answer. Dale Schoeller, a professor emeritus in the UW–Madison Department of Nutritional Sciences, was involved in a recent study where the research team measured the water turnover of more than 5,600 people of all ages spanned across 26 different countries to determine how variables play into water intake levels. They found that daily average needs ranged from one to six liters of water.  

By way of example, as described in a UW News article about the study, the researchers found that “All things equal, men and women differ by about half a liter of water turnover. As a baseline of sorts, the study’s findings expect a male non-athlete (but of otherwise average physical activity) who is 20 years old, weighs [154 pounds], lives at sea level in a well-developed country in a mean air temperature of [50 degrees Fahrenheit] and a relative humidity of 50%, would take in and lose about 3.2 liters of water every day. A woman of the same age and activity level, weighing [132 pounds] and living in the same spot, would go through 2.7 liters.” 

It’s important to also recognize that a person’s water needs will vary from day to day, especially if someone is losing water through sweat due to exercise or being outside on a hot day. Findings from Schoeller’s study found that “Physical activity level and athletic status explained the largest proportion of the differences in water turnover, followed by sex, the Human Development Index, and age.”

A helpful University Hospital article touches on some of these – and other – important factors to consider: 

• Where you live: People who live in hot, humid, or dry areas need more water. In addition, you may need more water if you live at higher altitudes. 
• Diet: People who drink a lot of coffee or other caffeinated beverages might lose more water through extra urination. They should consider drinking less caffeinated drinks and replacing them with water. Also, people who don’t eat many foods that are high in water (such as fresh or cooked fruits and vegetables) may need to drink more water. 
• Environment and time of year: If you spend a lot of time outdoors in the sun, in hot temperatures or even in overly heated indoor areas, you may need more water due to increased perspiration. Similarly, people often need to drink more water during warmer months than cooler ones. 
• Pregnant or breastfeeding: When you’re pregnant or nursing a baby, you need to drink extra water to stay hydrated, since your body is doing the work for two (or more). 

So, as you can see, there are many variables that come into play when determining each individual’s water needs. Again, there’s no one-size-fits-all! It’s important to consider your personal lifestyle and speak with a doctor if you have questions about how much water you should be drinking.