Residential propane storage issues are more complex than those for flammable and combustible liquids.
Permanent Storage System
If you want a permanent liquefied petroleum gases (LP-gas) system and tank installed in heavily populated areas, you must obtain a permit and comply with relevant installation codes. In addition, you will need to hire a state licensed contractor to perform the work and supply the equipment and product.
For portable Department of Transportation (DOT) Tank storage in an unattached garage or shed, you are allowed up to 300 lbs. total capacity. You may have either of the following:
Up to fifteen, 5-gallon (20-pound) portable appliance cylinder sized usually found on barbecue grills (DOT 4BA240)
Three 23-gallon (100-pound) cylinder (DOT 4BW240)
Or a combination of both not to exceed 300 lbs.
If you want to store propane and flammable/combustible liquids together, they should be separated by at least 10 feet.
You are only allowed to store two of the small portable (1-pound.) disposable propane cylinders inside your home or attached garage. (National Fire Prevention Association 58).
Propane cylinders attached to heating and/or cooking appliances, as well as those mounted on trailers, motor homes, and campers do not count towards your total storage capacity.