Does Drinking Water Increase Blood Cells? Separating Hydration Myths from Facts

December 24, 2025 •

4 min read

The human body is composed of over 50% water, with blood plasma being about 90% water, and adequate hydration is critical for overall health. However, the notion that drinking water increases blood cells is a widespread myth rooted in a misunderstanding of how hydration affects blood concentration.

Quick Summary

Drinking water does not increase the number of blood cells but maintains blood volume. Dehydration artificially concentrates blood cells, creating an illusion of higher counts that rehydration can correct.

Key Points

Dehydration Effect: Dehydration artificially increases blood cell concentration, not the actual number of cells, by reducing plasma volume.
Hydration's True Role: Proper hydration maintains optimal blood volume and viscosity, ensuring efficient circulation and nutrient transport.
Blood Cell Production: The production of new blood cells is primarily regulated by hormones like erythropoietin and depends on nutrients like iron, B12, and folate.
Normalization of Levels: Rehydrating with water can correct artificially high blood test results, such as elevated hematocrit, that are caused by dehydration.
Thicker Blood: Dehydration leads to thicker blood, which strains the heart and hinders the efficient delivery of oxygen and nutrients throughout the body.
Dietary Importance: For a genuine increase in blood cell count, focus on consuming iron-rich foods, not just increasing water intake.

The Composition of Blood and the Role of Hydration

To understand the relationship between water and blood cells, it's essential to first grasp the basic composition of blood. Blood consists of two main parts: blood cells (including red blood cells, white blood cells, and platelets) and plasma. Plasma, the liquid component, is roughly 90% water and acts as a transport medium for the cells, nutrients, hormones, and waste products throughout the body. Proper hydration ensures there is enough water to maintain an optimal blood plasma volume, allowing for efficient transport and circulation.

How Dehydration Affects Your Blood

When you become dehydrated, your body loses water faster than it can be replaced, leading to a decrease in blood plasma volume. This reduction in fluid volume does not change the actual number of blood cells, but it increases their concentration. This phenomenon is known as hemoconcentration. Blood appears 'thicker' or more viscous, and a blood test taken during a state of dehydration will show an elevated percentage of red blood cells relative to the total blood volume. This elevated reading is temporary and can be misleading, as it doesn't indicate an actual increase in production.

Dehydration decreases plasma volume, making blood more concentrated.
This leads to an elevated hematocrit reading, the percentage of red blood cells in the blood.
The effect is an illusion of a higher blood cell count, not a real increase in production.
Rehydrating corrects this issue, normalizing the plasma volume and blood concentration.

Where Do Blood Cells Really Come From?

So, if water doesn't increase blood cell production, what does? The answer lies in the bone marrow and specific hormones. The bone marrow is the primary site of blood cell production, a process called hematopoiesis. The production of red blood cells (erythropoiesis) is regulated by the hormone erythropoietin, which is primarily synthesized in the kidneys. Therefore, a person with a low red blood cell count (anemia) needs to address the underlying cause, which is often a deficiency in key nutrients, rather than simply drinking more water.

Here are the critical factors for healthy blood cell production:

Dietary Nutrients: Adequate intake of iron, vitamin B12, and folate is crucial for the body to produce healthy blood cells.
Hormonal Regulation: Erythropoietin signals the bone marrow to produce red blood cells in response to low oxygen levels.
Bone Marrow Health: The bone marrow must be healthy and functioning correctly for proper blood cell formation.
Addressing Underlying Conditions: Many medical conditions, from kidney disease to genetic disorders, can impact blood cell counts and require specific treatment.

Comparison: Hydration vs. Nutrient Intake for Blood Health


Aspect	Role of Proper Hydration	Role of Adequate Nutrient Intake	Role of Drinking Water Alone
Primary Effect	Maintains blood volume and optimal circulation.	Provides the building blocks for new blood cell production.	Corrects artificial concentration levels caused by dehydration.
Impact on Blood Cells	Keeps blood cells suspended in sufficient plasma for transport.	Directly supports the bone marrow in producing new red blood cells.	Does not initiate or speed up the production of new blood cells.
Result of Deficiency	Leads to hemoconcentration (artificially high counts) and poor circulation.	Can lead to a true deficiency of blood cells (e.g., anemia).	N/A (cannot cause cell deficiency, only affects concentration).
Relevance for Anemia	Supports treatment by ensuring efficient blood flow.	Directly addresses the nutritional cause of anemia.	Not a treatment for anemia; may even dilute hemoglobin readings.

Other Ways Water Affects Your Blood

Beyond maintaining plasma volume, water's impact on blood is more nuanced. Staying well-hydrated helps maintain blood at an optimal viscosity, or thickness. Thicker blood, resulting from dehydration, can increase the heart's workload and raise the risk of complications like blood clots. Conversely, while drinking more water can transiently thin the blood, a consistent, high intake doesn't significantly alter long-term blood viscosity in healthy individuals. However, in specific cases like those prone to blood clots, adequate hydration can be a helpful supporting measure.

Conclusion

In summary, the idea that drinking water increases blood cells is a myth. Water is vital for maintaining blood volume and ensuring efficient circulation, and dehydration can temporarily concentrate blood components, giving a false impression of a high blood cell count. The actual production of blood cells is a complex process controlled by hormones and requires specific nutrients like iron, B12, and folate. To genuinely increase your blood cell count if it is low, you should focus on a nutrient-rich diet, address any underlying medical conditions, and consult a healthcare professional. Staying hydrated is an essential component of overall health, but it should not be mistaken for a remedy for low blood cell counts.

For more information on the complexities of blood physiology and red blood cell disorders, the National Institutes of Health (NIH) is a reliable resource. https://www.ncbi.nlm.nih.gov/books/NBK526077/

Frequently Asked Questions

Drinking too much water can dilute the blood, which might cause blood test results to show an artificially low concentration of blood cells or hemoglobin, a condition known as hemodilution. This is not a true deficiency but a change in concentration.

Hemoconcentration is the condition where the concentration of blood cells increases relative to the plasma due to a decrease in fluid volume. It is a temporary state caused by dehydration.

Dehydration reduces blood plasma, leading to a higher percentage of red blood cells per unit of volume. This causes an elevated hematocrit reading, which is corrected once proper hydration is restored.

The fastest way to increase red blood cells depends on the cause of the low count. For nutritional deficiencies, increasing intake of iron, vitamin B12, and folate is key. A healthcare provider can provide an accurate diagnosis and treatment plan.

Yes, iron, vitamin B12, and folate are all essential for the body to produce healthy red blood cells. Deficiencies in these nutrients are a common cause of anemia.

Maintaining adequate hydration helps keep blood at an optimal, rather than thick, viscosity. While water intake can transiently decrease blood viscosity, it does not act as a long-term blood thinner in the same way as medication.

Common signs of dehydration include thirst, dry mouth, decreased and dark-colored urine, fatigue, and dizziness. More severe symptoms require medical attention.