Dehydration and Afib – How Much Water Should You Drink?

Woman smiling while sipping water out of clear bottle

Hydration is important to your overall health and significantly affects how efficiently your heart and cardiovascular system can deliver blood around the body. The body depends on a delicate balance of fluids for optimal function. This is called homeostasis. Drinking enough water supports the circulatory system to help ensure nutrients are delivered around the body (every cell needs them) and that waste is appropriately eliminated. Proper hydration is critical to blood pressure, heart rate, and electrolyte balance, each of which can make a big difference in heart health.

What is Afib?

Atrial fibrillation, or Afib for short, affects over 5 million Americans. It is a common heart rhythm disorder characterized by irregular and rapid heartbeats. The heart has four chambers: two upper (atria) and two lower (ventricles). The atria act as the heart’s pacemaker to keep the atria and ventricles in rhythm. In Afib, this irregular rhythm causes the atria and ventricles to lose synchrony, leading to symptoms such as palpitations, shortness of breath, dizziness, and fatigue. Afib also increases your risk for other complications like stroke and heart failure. Management of Afib can include medications, lifestyle modifications, and ablation procedures to restore normal heart rhythm.

What is Dehydration?

Our bodies are made up of 50-70% water. That means water is an integral part of the body’s normal functioning. Water in the body comes from the food you eat and beverages you drink, and it is lost through the skin (sweating), lungs (breathing), GI tract (digestion), and kidneys (urination).

Dehydration affects 17-28% of adults and occurs when the body loses more fluids than it takes in, leading to an imbalance in the body’s water content. When you’re dehydrated, your body lacks enough fluids to sweat, urinate, or even breathe properly. This can cause symptoms like thirst, dry mouth, fatigue, and dizziness. Severe dehydration is dangerous and may require medical attention. Drinking plenty of water helps maintain hydration.

Hydration’s Role in the Heart

Role of Water in Cardiovascular Function

Water helps the blood carry oxygen and nutrients to your cells while removing waste products. Without enough water, your heart must work harder, and your blood circulation may not be as efficient. When the heart works harder, the risk for Afib increases.

Impact of Hydration on Blood

When properly hydrated, your blood flows more easily because it’s not too thick or too thin. This means your heart doesn’t have to pump as hard to circulate blood throughout your body. Hydration also helps maintain healthy blood pressure by supporting blood volume in your arteries. Being well-hydrated helps regulate your heart rate, keeping it steady and within a healthy range.

Significance of Electrolyte Balance

Electrolytes like sodium, potassium, and calcium are essential for maintaining the electrical signals that control your heart rhythm. When electrolyte levels are out of balance, it can disrupt these signals and lead to irregular heartbeats, including conditions like a-fib.

How the Body Maintains a Fluid and Electrolyte Balance

Many systems in the body work together to maintain a balance by keeping water and electrolytes at appropriate levels.

  • The foods and beverages you consume contain water and electrolytes that your body uses to stay balanced.
  • When your body is low on fluids, it tells you to drink water by making you feel thirsty.
  • To maintain balance, your body gets rid of excess fluids and electrolytes through sweat and urine.
  • Kidneys adjust the amount of water and electrolytes in the body by keeping or getting rid of them through urine.
  • Hormones tell the kidneys when to hold onto water or let it go, depending on the body’s current needs.
  • Your body’s cells have ways to balance fluid and electrolyte levels.

How Much Water Should You Drink?

Adults should aim to drink at least 64 ounces (about 8 cups) of water daily, but individual needs vary based on age, weight, activity level, and climate. In general, older adults, those who are overweight, physically active people, and those living in hot or humid climates may need to drink more water to stay hydrated.

Tips for Staying Hydrated

Carry a reusable water bottle with you throughout the day as a reminder to drink water regularly.
Set hydration goals and track your water intake using apps or journals.
Drink water before, during, and after physical activity to replace fluids lost through sweat.
Include hydrating foods, such as fruits and vegetables with high water content, in your diet.

Common Myths

Myth: You only need to drink water when you’re thirsty.
Fact: Thirst is a late indicator of dehydration, so drinking water regularly throughout the day is important.

Myth: Everyone needs to drink eight glasses of water per day.
Fact: Fluid needs vary based on age, weight, activity level, and climate.

Myth: You can’t drink too much water
Fact: You can. Drinking too much water can throw off your electrolyte balance and damage your health. Speak to your doctor about the appropriate levels for you.

Myth: Drinking caffeinated tea or coffee is a net negative to your hydration
Fact: Tea and coffee both contribute to hydration. Yes, caffeine is a mild diuretic, but ultimately, what you put in more than makes up for what caffeine causes you to eliminate

Maintaining proper hydration is important for overall cardiovascular health. Adequate water intake ensures optimal blood circulation, nutrient delivery, waste removal, blood pressure regulation, heart rate, and electrolyte balance, all vital for heart function. Dehydration can exacerbate Afib risk by straining the heart and disrupting electrolyte balance. The recommended water intake differs for each person, but drinking eight glasses of water a day is a good start. By prioritizing hydration—thus avoiding dehydration—your heart will continue to function efficiently and decrease your risk of developing Afib.


  1. Chuda A, Kaszkowiak M, Banach M, Maciejewski M, Bielecka-Dabrowa A. The Relationship of Dehydration and Body Mass Index with the Occurrence of Atrial Fibrillation in Heart Failure Patients. Frontiers in Cardiovascular Medicine. 2021;8. doi:
  2. American Heart Association. Staying Hydrated – Staying Healthy. Published January 22, 2024.
  3. Tobias A, Mohiuddin SS. Physiology, Water Balance. PubMed. Published October 3, 2022.
  4. Taylor K, Jones EB. Adult Dehydration. PubMed. Published October 3, 2022.
  5. American Heart Association. We All Need Water for a Healthy Life – But How much? Published June 8, 2018.
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