How much water does AquaTru hold? November 23, 2019 07:30 Updated Follow The tap water tank holds about a gallon of water, and the clean water tank holds about 3 quarts of purified water. Related articles Can I get a bigger water tank? How much does AquaTru weigh? How quickly does AquaTru work? How do I know when to change my filters? What are the dimensions of the AquaTru?