Contaminated tanks can find their way into the propane market through the tank exchange system common at many retailers. Buyers commonly drop off an empty tank and pick up a full one.

But how do you know how much propane is left in the tank? Most propane tanks don't come with a gauge to let you know how much fuel is remaining.

Keeping a propane tank at home can be dangerous if you don't know how to store, use, and handle it properly. Here are some common mistakes to avoid.