How Much Water Should I Drink? What Research Says About Staying Hydrated

September 10, 2026

By Bragg Staff

Reviewed By Emilio Villarreal, Director of Technical Services

How Much Water Should I Drink? What Research Says About Staying Hydrated

It's one of the most common health questions, and one that doesn't have a one-size-fits-all answer.

You've probably heard recommendations ranging from drinking eight glasses of water a day to consuming half your body weight in ounces. But if you've ever wondered which advice is actually backed by science, you're not alone.

The good news is that several respected health organizations have developed evidence-based recommendations to help people understand their daily fluid intake and hydration needs. Rather than prescribing a single amount of water for everyone, these guidelines recognize that the amount of water a person needs depends on a variety of factors, including age, sex, body weight, physical activity, climate, and overall health.

So, how much water should you drink? Let's look at what the research and the organizations that study hydration actually recommend.

What Do Experts Recommend for Daily Water Intake?

One of the most frequently cited sources of hydration recommendations is the National Academies of Sciences, Engineering, and Medicine, which publishes Dietary Reference Intakes for water and other nutrients ^[1].

Rather than recommending that everyone drink the same amount of plain water, the National Academies provide Adequate Intake (AI) recommendations for total daily fluid intake. These recommendations include fluids from beverages (including drinking water, tea, milk, and other beverages) as well as the water naturally found in foods.

For healthy adults, the current recommendations are:

About 3.7 liters (125 ounces) of total fluid per day for men
About 2.7 liters (91 ounces) of total fluid per day for women

It's important to note that these values are intended as general guidelines, not individualized prescriptions. According to the National Academies, fluid needs vary considerably from person to person, and many healthy individuals meet their hydration needs simply by drinking when they're thirsty and choosing beverages and foods that contribute to their overall daily fluid intake.

The National Academies also estimate that, for most adults, about 20% of total water intake comes from food, with the remaining 80% coming from beverages. That means staying hydrated isn't just about what's in your water bottle; it's also influenced by the foods you eat throughout the day.

What Factors Influence How Much Water You Need?

Even within these general guidelines, how much water an individual actually needs can vary quite a bit from person to person.

That's because there isn't a single amount of water that's appropriate for everyone. Research suggests that fluid needs vary considerably between individuals, reflecting differences in physiology, lifestyle, and environmental conditions rather than a single characteristic ^[2].

Body Weight

Body size is one factor that can influence fluid needs because larger bodies generally have greater total body water and water turnover. Research tracking water turnover in over 5,600 people worldwide found that body size and composition were among the strongest predictors of how much water a person uses each day, alongside physical activity, climate, and other factors ^[3].

In other words, body weight alone cannot determine how much water someone should drink, since hydration needs are influenced by many physiological and environmental factors working together.

Physical Activity

One of the biggest influences on fluid needs is physical activity.

During exercise, the body loses water through sweating as part of its normal thermoregulatory process. The amount of fluid lost varies depending on the intensity and duration of exercise, environmental conditions such as heat and humidity, clothing, and individual sweat rate ^[4].

As a result, people who exercise regularly or spend extended periods outdoors may need to drink more fluids to replace water lost through perspiration ^[4].

Climate and Environment

Where you live and the conditions around you can also influence your fluid needs.

Hot weather and high humidity can increase water losses through sweating and breathing. As temperatures rise or environmental conditions become more demanding, the body may need additional fluids to help replace those losses and support a steady internal temperature. This holds true across a wide range of climates and populations, from hot and humid regions to high altitudes ^[3].

Health Conditions and Life Stage

Women who are pregnant or breastfeeding generally need more fluids than other adults to support the increased physiological demands of these life stages ^[5].

Additionally, older adults may be at greater risk of dehydration because aging is associated with changes in thirst perception, kidney function, and the body's ability to maintain fluid balance, making it easier to become dehydrated if fluid intake is inadequate ^[6].

How Can You Tell If You're Drinking Enough Water?

Because hydration needs vary from person to person, many experts recommend looking beyond the number of glasses you drink each day.

Instead, several practical indicators can help you assess your hydration status.

One of the most commonly used is urine color. According to the National Institutes of Health, light yellow urine generally suggests adequate hydration for most healthy adults, while darker urine may indicate the body needs more fluids ^[7].

Thirst is another important signal.

The body's thirst mechanism helps maintain fluid balance, encouraging us to replace water as it is lost throughout the day. However, researchers note that thirst doesn't always appear immediately after fluid loss, which is one reason older adults and people participating in prolonged exercise may need to be especially mindful of hydration ^[7].

Other signs that may suggest you're getting enough water include:

Regular urination throughout the day
Comfortable energy levels
Normal bowel movements
Feeling refreshed after drinking water with meals and throughout the day

It's also important to recognize that hydration can't be measured by a single sign. Urine color, thirst, medications, certain foods, vitamins, and individual health conditions can all influence these indicators ^[7]. Rather than aiming for perfect hydration every day, experts recommend focusing on consistent fluid intake while adjusting for changes in activity, weather, and overall health ^[1].

What Are the Health Benefits of Staying Hydrated?

Water is involved in nearly every major physiological process in the body.

Research has shown that adequate hydration supports several important functions, including:

Supporting a Healthy Body Temperature

One of water's most important roles is helping the body maintain a steady internal temperature. As body temperature rises during exercise or exposure to heat, sweating cools the body through evaporation. Replacing these fluid losses helps support this natural cooling process ^[8].

Supporting Circulation and Blood Pressure

Water helps maintain blood volume, which is important for circulation. When fluid losses become significant, blood volume may decrease, contributing to symptoms of dehydration, including dizziness and low blood pressure in some individuals. Research on the effects of water on blood pressure regulation supports the connection between hydration status and circulatory function ^[9].

Cushioning Joints and Protecting the Spinal Cord

Water is a major component of synovial fluid, which helps cushion joints ^[10], and of cerebrospinal fluid, which helps protect the brain and spinal cord from mechanical injury ^[11].

Supporting Overall Body Function

Water also plays an essential role in transporting nutrients, removing waste through urine, supporting cellular processes, and helping the body function properly every day ^[12].

Rather than offering one dramatic health benefit, staying hydrated supports many interconnected processes that help the body function as it should.

What Happens If You Don't Drink Enough Water?

The body continuously loses water throughout the day through breathing, sweating, urination, and bowel movements. When these losses aren't replaced, dehydration can occur ^{[13], [14]}.

Mild dehydration may contribute to symptoms such as:

Thirst
Dry mouth
Fatigue
Headache
Darker urine
Reduced physical performance

The Bottom Line

If you've ever wondered, "How much water should I drink?", you're not alone.

The truth is, there isn't a one-size-fits-all answer. Your hydration needs naturally change based on your daily routine, activity level, environment, age, and overall health, among several other factors. The goal isn't to chase a perfect number; it's to consistently give your body the fluids it needs to function at its best.

The good news is that staying hydrated doesn't depend on plain water alone. Water-rich foods, herbal teas, milk, and other nourishing beverages can all help you meet your daily fluid needs as part of a balanced lifestyle.

At Bragg®, we believe wellness is built through simple, intentional habits that support the body every day. Hydration is one of those foundational habits, and it fits naturally into a broader wellness routine alongside balanced meals, movement, and rest. When you make it a priority to nourish your body with adequate fluids, wholesome foods, and mindful daily choices, you're supporting its natural ability to thrive.

Because lasting health isn't created through perfection or complicated rules, it's built one healthy choice at a time.

Hydration is just one piece of a healthy lifestyle. If you're looking to build sustainable wellness habits, these Bragg resources offer practical tips and science-backed guidance to help you feel your best every day.