3 Ways to Properly Dispose of Cooking Oil, According to Experts

Cooking oils are an essential ingredient in so many recipes and you'll find them in every home cook's pantry. Not only does oil evenly distribute heat, but it also adds flavor and prevents food from sticking to pans. However, it can also be one of the trickiest (and messiest!) ingredients to handle, especially if you're deep-frying fan favorites like chicken fingers or donuts. So, what's the best way to toss cooking oil? Ahead, professional chefs explain how to dispose of cooking oil properly, plus how to safely reuse it.

Why You Should Never Pour Cooking Oil Down the Drain

After frying food, pouring the leftover oil down the sink might seem like an easy way to clean up—but it's one of the worst things you can do to your plumbing. Cooking oil, regardless of the type, can solidify and clog sewer pipes, potentially leading to messy backups. Similarly, cooking oil can solidify in septic tanks, causing pricey septic issues.

How to Dispose of Cooking Oil Properly

For many home cooks, the most convenient way to discard cooking oil is to toss it in the trash. Here's the best method, according to Stephen Mandracchia, director of culinary operations at the Institute of Culinary Education in New York City:

1. Let the cooking oil cool.
2. Pour the oil in an empty resealable container, such as a milk carton.
3. Seal the container properly, then put it in the trash.

If you don't have an empty milk carton, any sturdy, non-recyclable container will do, says Jonathan Poyourow, chef and associate professor at Johnson & Wales University in Providence, Rhode Island. Make sure it has a secure lid to prevent leaks. Other examples include empty milk jugs, detergent bottles, plastic containers, and glass jars with screw-top lids, says Poyourow.

"Avoid using paper or thin plastic bags, as they can tear or leak," says Poyourow. However, you can line the sturdy container with a plastic bag for extra protection, he notes.

In the Compost

Composting cooking oil isn't recommended, though it can be done in very small amounts, says Mandracchia. The reason? "Cooking oil can create a barrier that prevents proper breakdown [of the compost]," explains Mandracchia. It may also attract pests.

If you decide to compost small amounts of oil, follow these best practices, according to Poyourow:

• Only compost oil 1 to 2 tablespoons at a time to avoid overwhelming the pile.
• Filter the oil through a fine mesh strainer or cheesecloth. This will help remove food particles.
• Mix the oil with high-carbon materials (such as sawdust, shredded newspaper, or dry leaves), which will help absorb the oil and break it down.
• Avoid pouring oil directly onto the compost pile. Otherwise, it can clump together and create an environment that prevents proper decomposition.
• Turn the compost pile regularly to aerate the materials and promote even breakdown.

At a Recycling Center

The most eco-friendly method for discarding cooking oil is to recycle it. To do this, you'll need to bring the used oil to an establishment that recycles cooking oil.

"There are commercial services that collect and recycle used cooking oil from restaurants and larger facilities," explains Mandracchia. But for home cooks, it's best to look for a curbside recycling program or other local drop-off location, he says. "Used cooking oil is generally repurposed into biodiesel fuel, one of the cleanest and purest fuels available," adds Mandracchia.

 If you'd like to recycle your oil, here's how you should prepare it, according to Poyourow:

1. Cool the oil completely to prevent spills or safety hazards.  
2. Pour the oil into a clean, dry, and leak-proof container. Great options include plastic jugs with screw-top lids, metal cans with tight lids, and sturdy glass jars (if it can be transported safely).
3. Label the container with "used cooking oil," if required by the recycle center.
4. Ensure the container is sealed tightly to avoid leaks.
   

"Some recycling centers or biodiesel programs provide specific collection containers or have designated drop-off stations," says Poyourow. "Always check their guidelines before dropping off oil."

Can You Reuse Cooking Oil?

You might be surprised to learn that you can reuse cooking oil before throwing it out. It's the best way to get the most out of your oil—though there are several things to keep in mind.

• In general, neutral oils with high smoke points (think canola, peanut, and sunflower oil) are best for reusing. "Avoid oils with strong flavors (e.g., olive oil) or low smoke points, as they degrade more quickly," says Poyourow.
• When possible, maintain a frying temperature between 350 and 375 degrees Fahrenheit to minimize oil degradation. "Use a thermometer to monitor temperature and avoid overheating," suggests Poyourow. You can also use a deep fryer with a temperature control feature or a heavy-bottomed pot to ensure the heat is evenly distributed.
• Avoid using thin or lightweight pans, as they cause temperature fluctuations, notes Poyourow.

How to Properly Reuse Cooking Oil

"While frying oil takes on the flavor of whatever it originally fried, it can be reused two to eight times if handled properly," explains Mandracchia. Here's how to do it, according to Poyourow:  

1. Let the oil cool completely.
2. Filter the oil through a fine-mesh sieve, cheesecloth, or a coffee filter. This will help remove food particles that can promote spoilage.
3. Store the container in a cool, dark place, such as the pantry or refrigerator, to help slow degradation.
   

When to stop reusing the oil: Toss the oil when it becomes dark or cloudy, develops an off-smell, or foams excessively during frying, says Poyourow.