TL;DR
Old gasoline goes to a household hazardous waste facility, never down a drain, on the ground, or in the trash. A gas can that has held fuel is never truly clean, so replacement is usually the honest answer. A modern approved can costs less than the risk of a bad one.
Start with the safety frame
Gasoline vapor is the hazard, not the liquid. Vapor is heavier than air, it travels along the ground, and it can find an ignition source many feet away from where you are working.
Everything here happens outdoors, in open air, with no flame, no pilot light, no water heater, no smoking, no power tools, and no running engine anywhere nearby. Not in a garage. Not in a shed.
Wear nitrile gloves and eye protection. Gasoline strips skin oils and is absorbed through skin, and it is genuinely bad for eyes.
Keep a working fire extinguisher rated for flammable liquids within reach, and know where it is before you start rather than after.
Old gasoline: where it actually goes
Gasoline degrades. It typically stays usable for a few months in a sealed container, and stabilizer extends that, but old fuel oxidizes, forms gum, and separates. It also picks up water out of the air, and ethanol-blended fuel does this faster.
Old gas that is dark, cloudy, sour smelling, or has visible water or sediment in it is done. Running it through an engine causes carburetor problems that cost more to fix than the fuel was ever worth.
Where it goes: a household hazardous waste facility. Most counties operate one, and many run collection events. Some auto shops and fuel retailers accept small quantities. Call ahead and ask, because acceptance rules vary and containers matter.
Where it never goes: down a sink, a floor drain, a storm drain, a septic system, onto soil, into a fire, into household trash, or mixed with other chemicals. Fuel in a drain contaminates water and creates explosion risk in the sewer system. Source: U.S. Environmental Protection Agency household hazardous waste guidance.
Transport it in the sealed can, upright, in the trunk or bed rather than the passenger compartment, and go straight there.
How do you clean a gas can?
Empty it completely at a hazardous waste facility, then let it air out with the cap and spout removed for several days outdoors in a shaded, ventilated spot. If residue remains and the can is worth keeping, swirl a small amount of hot water with a grease-cutting dish soap inside, pour that off into a container for hazardous waste, rinse the same way, and air dry it fully for days.
Note that the rinse water is contaminated. It goes to hazardous waste too, not down a drain, which is why many people skip this step entirely and replace the can instead.
Do not add gravel, nuts and bolts, sand, or chain to scour the interior. Metal moving in a fuel container can create a spark, and static in a plastic can is its own risk.
Never use solvents, never use bleach, and never mix anything with fuel residue. Never introduce a flame, a heat gun, or compressed air into a can that has held gasoline. Vapor plus ignition is exactly the failure everyone is trying to avoid.
When to just replace it
For most households, replacement is the right call, and here is why.
Plastic cans absorb hydrocarbons into the material itself. A can that has held gasoline will smell like gasoline essentially forever, and no cleaning changes that. If your goal is to store water, kerosene, or anything else in a former gas can, replacement is the only correct answer.
Replace it, without hesitation, if the can is cracked, brittle, sun-faded, or chalky; if the spout leaks, is missing, or no longer seals; if the cap or vent is damaged; if it is a metal can with interior rust; or if it is old enough that you cannot remember buying it.
Sunlight degrades plastic fuel cans over years, and a brittle can splits at the worst possible moment. Modern approved containers include flame arrestors and automatic-closing spouts that older cans do not have.
A can holding old fuel that you do not want to deal with can often go to the hazardous waste facility as-is, fuel and all. Ask them.
Cleaning the spout and the outside
The spout is where most of the mess actually lives, and it is worth attention.
Take the spout assembly apart if it comes apart, and wipe each piece with a rag and a little hot soapy water. Check the gasket or O-ring, because a hardened one is why the can drips down its own side.
Wipe the exterior of the can with warm soapy water on a rag, dry it, and check the label and the date if there is one. Rags used on fuel are the hidden hazard in this whole job: oily rags can self-heat and ignite, so spread them flat outdoors to dry before disposal, or seal them in a metal container with a lid. Never wad them in a trash bag in a garage.
Storing fuel so it stays usable
Store gas cans outdoors in a detached shed if you can, never inside the house, never in a basement, and never near a water heater, furnace, or any pilot light.
Keep them out of direct sun and off bare ground. Store upright with the cap tight and the spout sealed.
Buy only what you will use in a season, and add stabilizer if it will sit. A smaller can that turns over often is better than a large one that goes stale.
Label cans clearly, especially in a household with mixed fuel for two-stroke equipment. Putting the wrong mix in an engine is an expensive mistake.
The same ignition-source discipline governs everything with fuel in it, whether you clean the exterior of a portable generator or clean the outside of a propane tank. Our guide on how to clean outdoor gear, grills, and patio equipment covers the wider set, and yard and equipment work always tracks back into the house, which is where regular house cleaning keeps up.
FAQ
How do you dispose of old gasoline?
Take it to a household hazardous waste facility. Most counties run one, and many hold collection events. Some auto shops accept small quantities, so call ahead since rules vary. Never pour fuel down a sink, storm drain, or septic system, onto soil, into a fire, or into household trash.
Can you clean a gas can well enough to use it for water?
No. Plastic fuel containers absorb hydrocarbons into the material, so a can that has held gasoline will always carry that residue and odor regardless of cleaning. If you need a container for water or any other liquid, buy a new one made for that purpose.
How long does gasoline last in a can?
Typically a few months in a sealed container, with fuel stabilizer extending that considerably. Ethanol-blended fuel absorbs water from the air and degrades faster. Fuel that is dark, cloudy, sour smelling, or has visible water or sediment should be taken to hazardous waste rather than used.
What should you never use to clean a gas can?
Never use solvents, bleach, a heat gun, compressed air, or an open flame anywhere near a can that has held gasoline, because fuel vapor plus ignition is the whole hazard. Do not add gravel, nuts, or chain to scour the inside either, since metal moving inside can spark.
When should you replace a gas can instead of cleaning it?
Replace it if it is cracked, brittle, sun-faded or chalky, if the spout leaks or is missing, if the cap or vent is damaged, if a metal can has interior rust, or if you cannot remember when you bought it. Modern approved cans include safety features older ones lack.
How do you dispose of rags used on gasoline?
Spread them flat outdoors to dry completely before disposal, or seal them in a metal container with a tight lid. Oily rags can self-heat and ignite, so never wad them into a trash bag or leave them piled in a garage. Ask your hazardous waste facility about heavily soaked rags.
Where should you store a gas can?
Outdoors in a detached shed when possible, upright, out of direct sun and off bare ground, with the cap tight and the spout sealed. Never inside the house, never in a basement, and never near a water heater, furnace, or any appliance with a pilot light.
Equipment and fuel season always leaves the house needing its own attention. Otesse is local, sends background-checked crews, and gives you upfront pricing with no hidden fees. Every home is different, so the real number depends on size, condition, and what you want covered. Get a quote and we will walk you through it.