What is the effect of drinking water on the density and/ or viscosity of blood?
Hydration plays a big part in the viscosity of blood. While such fluctuations may not be visible to the naked eye, even when blood is looked at or touched outside of the body, hemoconcentration analysis can reveal significant changes in blood viscosity. When a person is dehydrated, the viscosity of the blood increases because there is less water in the composition. Just the same, when a person is well hydrated, their blood viscosity decreases.
"Density" would be another way to describe the concentration of non-liquid components of blood like platelets, red blood cells, and white blood cells. In a person who is dehydrated, the lack of water results in increased hemoconcentration and viscosity.
People who are at risk of diabetes, stroke, or heart disease can benefit from increasing their intake of water.
Not everyone has the same requirements for staying hydrated, but a good rule of thumb is to try to drink 64oz per day, plus an extra 8oz for every caffeinated beverage drank. The best way to make sure you're staying hydrated is simply to drink water when you feel thirsty. Eating fresh fruits and vegetables can also help bring water into the body.