Propane tanks must be outside and at least 10 feet from a building opening such as a window, door, vent, etc. Tanks from 500 – 2000 gallons are set 25 feet away from a building or property line. 2000+ gallon tanks are 50 feet away from a building or property line.
Please do not store your barbecue tanks in a garage, as it is against the fire code. Just keep them outside in a safe place.