How to Store Gasoline Safely for Generator Backup Power

Every gasoline generator owner eventually faces the same dilemma: you need fuel on hand before the storm, because gas stations without power cannot pump, but gasoline is volatile, it degrades, and storing it wrong is a genuine fire hazard. The goal is to keep enough fresh fuel to get through the first days of an outage without turning your garage into a risk. This guide covers how much to store, which containers to use, where to keep them, how long fuel lasts, and a simple rotation system that keeps your supply fresh without waste.

How much gasoline should you keep?

Start with your generator’s fuel consumption at the load you expect. A mid-size portable running essentials at about half load might use 0.4 to 0.7 gallons per hour. If you plan to run it 12 hours a day, that is roughly 5 to 8 gallons daily. Two to three days of fuel is a reasonable target for many households, because stations usually reopen or get resupplied within that window in most outages.

Also check local rules. Many fire codes limit residential gasoline storage, commonly to around 25 gallons in approved containers within a home’s attached garage, with stricter limits in some cities and apartment settings. Check with your local fire department before stockpiling.

Choose the right containers

• Use approved gas cans that meet current safety standards, typically marked with UL, ASTM or similar certification. Red is the standard color for gasoline.
• Stick to 5-gallon or smaller cans. A full 5-gallon can weighs about 30 pounds, which is manageable when refueling a generator.
• Look for flame arrestors in the spout or neck, a mesh that helps prevent flashback into the can.
• Metal safety cans with spring-loaded lids cost more, often $60 to $120, but are the most durable and self-venting option.
• Never use milk jugs, water bottles or unlabeled containers. They degrade, leak and create confusion.

How long gasoline lasts

Heat and air shorten fuel life. Full cans with minimal air space and cool storage last longest.

Where to store it

The best location is a detached shed or outbuilding with ventilation, away from the house. If that is not possible, an attached garage is the next choice, following local limits. Wherever you store it:

• Keep cans away from ignition sources: water heaters, furnaces, clothes dryers, workbenches with power tools, and pilot lights. Gasoline vapor is heavier than air and can travel along the floor to a flame.
• Keep cans out of direct sunlight and away from heat, which builds pressure and speeds degradation.
• Never store gasoline inside living areas or basements.
• Store cans off concrete on a shelf or pallet, upright, with caps tight.
• Keep a multipurpose fire extinguisher, rated ABC, within reach but not right next to the cans.
• Store fuel where children and pets cannot reach it.

Filling cans safely

At the pump, always place the can on the ground before filling, never in a truck bed or car trunk. Static electricity can build up in a can on a plastic bed liner and ignite vapor. Keep the nozzle in contact with the can while filling, fill to about 95 percent to allow expansion, and add stabilizer right away if the fuel is for storage.

A rotation system that works

1. Label each can with the fill date and whether it has stabilizer.
2. Every three to six months, pour the oldest can into your car’s tank and refill it with fresh fuel and stabilizer.
3. Use the generator’s monthly exercise run to consume some stored fuel as well.
4. Keep a funnel, stabilizer and rags with the cans.

This way no fuel sits longer than about six months, and nothing goes to waste.

Refueling the generator

Shut the generator off and let it cool for several minutes before refueling; gasoline spilled on a hot muffler can ignite. Refuel outdoors where the generator runs, which should be at least 20 feet from the house with exhaust pointed away from openings, never in a garage or on a porch. Wipe up spills before restarting.

FAQ

Can I store gasoline in my car for emergencies?

Keeping your vehicle’s tank topped up before a storm is a smart source of backup fuel. Storing cans inside a car, especially in summer heat, is not recommended because vapor can build up in the enclosed cabin.

How do I dispose of old gasoline?

Take it to a household hazardous waste collection site. Never pour it on the ground or down a drain. Slightly old, stabilized fuel can often be blended into a vehicle tank a little at a time.

Bottom line

Store two to three days of generator fuel in approved 5-gallon cans, within your local fire code limit, in a ventilated space away from ignition sources and never inside living areas. Treat fuel with stabilizer, label cans with dates, and rotate every three to six months into your car. Fill cans on the ground and refuel only when the generator has cooled.