At 515 pounds when filled with water, you'd want to make sure your tank is on a stable ground. It probably will be fine if you Put the tank on the joints of the house or pillars should help, also along with a good stand to help distribute weight. If you're still unsure, it's best to either talk to your landlord or other informed person on the house, or better safe than sorry put in the basement if possible. Best put it there yourself than the tank coming downstairs on it own through the floor.