Dear Eco-Monkey >> What should I do with my little portable camping propane canisters? Since they’re metal, I assume you can recycle them, but they also seem like a fire or explosion hazard.

Thanks, Micah

Dear Micah >> Great question — and you’re right to be cautious. While it might seem like your curbside recycling bin or local scrap metal yard would accept your tiny tank, this is one item you definitely don’t want to toss in with the tin cans. Propane is highly flammable, and even “empty” canisters can pose a serious explosion risk if punctured or crushed during collection or processing.

That means: never put propane tanks — large or small — in your trash or recycling bin. A single spark could ignite a fire in a collection truck or at a recycling facility, endangering workers and causing costly damage. Scrap metal recyclers also generally won’t accept them for this very reason.

Instead, small propane canisters like those used for camping stoves must be disposed of at a hazardous waste facility. If you live in Boulder or Broomfield County or Erie, you can drop them off for free at the Boulder County Hazardous Materials Management Facility (1901 63rd St., Boulder, open Wed—Sat, 8:30 a.m.—4:30 p.m.). Be sure to bring proof of residency like a license or utility bill.

For your next camping adventure, consider switching to a refillable cylinder or using a refill adapter that lets you refill small canisters from a larger propane tank. These can be purchased at the Boulder County Hazardous Materials Management Facility or REI and refilled at any propane refill center — an excellent way to fire up the camp stove without burning through single-use tanks.

Larger propane tanks (5 pounds or more) used for grills are generally designed to be refilled. Local service centers like Clark’s Propane Service in Hygiene and Fred’s Propane Service in Boulder will refill your tank for a small fee. Both will also recycle old tanks (free at Clark’s, $10 at Fred’s). U-Haul will refill small tanks, too, but doesn’t accept them for recycling.

In general, always keep gas and other explosive materials out of your municipal trash and recycling bins. Contact your local sheriff’s office before moving or trashing items like ammunition, flares, or fireworks — they’ll often accept these for safe disposal.

And as always, if you’re not sure whether a material goes in the recycling bin, the compost bin, the trash or to a drop-off facility, consult the Eco-Cycle A-Z Recycling Guide or the Waste Wizard in Longmont.

— Eco-Monkey

— Got Zero Waste questions? Email Eco-Cycle at recycle@ecocycle.org or call 303-444-6634.