Is it normal to have high albumin levels even if you drink a gallon of water a day and are on a vegetarian diet?

Unlikely: A serum albumin test measures the amount of protein in the clear liquid portion of your blood. Albumin is a protein made by the liver; the test is often used to evaluate liver function, nutritional status and other conditions. Under (not over) hydration would more likely affect albumin; vegetarian diets can/should be completely adequate and not usually associated with low albumin. Hope this helps