Yes, drinking water is allowed and even encouraged when fasting for blood work. Water does not affect blood test results and helps keep you hydrated, making it easier for the person drawing your blood to find veins. However, you should avoid all other beverages, such as coffee, juice, or flavored drinks, as they can affect the accuracy of the test results. Typically, fasting means not eating or drinking anything except plain water for 8-12 hours before the blood test, depending on the specific instructions for the test you are taking.