How to Properly Dispose of Cooking Oil
Oil is a key ingredient in the kitchen, especially for making fried delicacies. So whether you’re an avid home cook or just like to indulge from time to time, there may be times when you find yourself with more leftover oil than you know what to do with.
You may be wondering whether you can reuse cooking oil or recycle it, especially if you used several gallons of oil to fry up a batch of fries. You’ll be happy to learn that there are several ways to dispose of cooking oil that don’t include pouring it down the drain. You can even recycle oil, reuse cooking oil if it’s still clear, or reseason your pans with used oil so it doesn’t go to waste.
If not properly disposed of, cooking oil and animal fats can have consequences for both the environment and your home. So make your lifestyle a little bit greener by keeping oil out of your sink!
Photo by Ashwini Chaudhary
Why properly disposing of cooking oil is important
It may not seem like a big deal to wash off a pan with a layer of oil in it, or to pour a small amount of bacon grease down the sink, but small amounts of oil can easily build up in your pipes over time. It doesn’t matter whether you use hot water to wash it down or add lots of soap; the oil will eventually solidify and cling to the sides of pipes. As the oil builds up, it can cause blockages and backups in the pipes that require the help of expensive professionals.
Additionally, disposing of cooking oil, grease, or animal fats in a way that it ends up in the soil or water, could cause serious harm to already fragile ecosystems and wildlife.
To avoid clogging pipes
There are many different kinds of oils and fats – some are plant-based (e.g. sunflower seed oil), some are animal-based (e.g. bacon fat), and some are petrochemical (e.g. fossil fuels) – but they all share some basic properties. Oils and fats are primarily made up of hydrocarbons, they are hydrophobic (water repellent), and they are often (but not always) liquid at room temperature.
A key property of oil is that it becomes solid at cooler temperatures. Even though it may seem like no big deal to pour a liquid oil or fat down the drain, the fact is that it doesn’t remain liquid when it enters those cool pipes. As the oil works its way down, molecules cling to the sides of your pipes and can eventually cause a blockage.
Just like when fatty materials such as fats or cholesterol build up on the walls of arteries and lead to a heart attack or stroke, a blockage in sewage pipes is no small matter. A sewage backup can cause flooding in your home or somewhere further down the line, and it can be expensive to fix as these pipes are often buried deep in the ground and are difficult to replace.
If you know that you regularly wash pots or pans coated in oil or grease, it may be a good idea to install a grease trap under the sink or outside the home. Grease traps designed to remove oil and grease from wastewater, and can help protect your pipes as well as the city’s pipes from oil buildup.
To protect fragile ecosystems and wildlife
Do you remember the Deepwater Horizon oil spill of 2010? Unfortunately, oil spills of all kinds and sizes happen all the time, according to the National Oceanic and Atmospheric Administration (NOAA). And it’s not just petroleum oil that we’re talking about. Cooking oils, animal fats, and other non-petroleum oils are all harmful to the environment and wildlife. In fact, they’re all placed under the same regulations by the Environmental Protection Agency (EPA).
Some of the harmful effects of oil in the environment include:
Physical harm of plants and animals by blocking oxygen, preventing flight (in birds), or impeding insulation (of a sea otter’s fur, for example)
Oil toxicity in animals when digested, leading to various health problems or even death
Producing rancid odors
Clogging of water treatment plants
Causing fire
Formation of toxic compounds or byproducts
Destruction of fragile habitat and food supplies
Despite the efforts of valiant rescue operations, it’s extremely difficult and inefficient to rescue animals once they’ve been harmed by oil in the environment. While petroleum oil spills are the biggest source of oil in the environment, it’s equally important to properly dispose of home cooking oils and grease.
Can you reuse cooking oil?
If you’re left with a large amount of cooking oil after frying up a batch of french fries, there’s a good chance that you can reuse that oil at least once or twice before having to dispose of it. Being able to reuse cooking oil or grease is a great way to reduce waste and make the most of your money, as cooking oil is not cheap.
There’s no hard and fast rule for reusing cooking oil; factors such as what temperature it was heated to and for how long, as well as what was cooked in it, all impact its quality. Fortunately, it’s pretty easy to tell when you can reuse cooking oil by asking the following questions:
Does it smell “off” or rancid?
Is it discolored?
Does the oil contain a lot of solids or debris?
Has it already been reused more than once?
If you answered no to all of those questions, the oil is probably safe to reuse. If you answered yes to any of those questions, it’s best not to take your chances with that batch of oil. According to this study, oil reheated to its boiling point multiple times starts to generate free radicals that can have harmful effects on the body. For this reason it’s best not to reuse cooking oil more than 3-4 times even if it remains clear and odor-free.
Tips for safely reusing cooking oil
If you’ve determined your cooking oil is safe to reuse, it’s important to follow a few steps to make the most of it.
Start by straining the oil through a fine mesh strainer, cheesecloth, or coffee filter to strain out any solid particles and debris. Store the strained oil in a sealed glass container or jar, and label it with a date and the type of food that was cooked in it, as you probably don’t want to cook donuts in oil that was used to cook meat or something else with a strong flavor.
It’s best to store used cooking oil in the refrigerator to avoid it going rancid. Use it within a few weeks for best results.
You can also reuse your cooking oil for other things besides cooking; use it to reseason your cast iron pans, for example!
How not to reuse cooking oil
Some how-to or DIY guides will suggest reusing cooking oil around the home, for instance to recondition old leather, oil wooden furniture, or lubricate hinges.
However, it’s best to avoid using cooking oil – especially used cooking oil – for these tasks, as it’s likely to go rancid and let off noxious fumes. Stick to the products that have been designed for these uses, and instead keep the cooking oil in the kitchen.
Can you compost cooking oil or grease?
While cooking oils derived from plants may seem like a fine addition to the compost pile, you should not compost cooking oil, bacon grease, or other fats.
While small amounts of oil (such as oily residue on leftovers) are okay in compost, you don’t want to pour used cooking oil into compost or on your soil. Not only can oil attract unwanted critters, but it can create a hydrophobic barrier within the compost system that blocks out air and makes your compost anaerobic instead of aerobic. There’s also evidence that oil contaminates soil and negatively impacts soil life.
3 ways to safely dispose of cooking oil and grease
Now you know why people say you shouldn’t pour cooking oil or bacon grease down the sink (or flush it down the toilet, for that matter). So what can should you do with used cooking oil?
When your cooking oil or grease is ready to be disposed of – reused or not – you have three readily available options for getting rid of it safely and responsibly:
Pour into a sealable container and toss it in the trash
The easiest method for disposing of used cooking oil is pouring it into a sealable container and tossing it in along with your household garbage. Just follow these easy steps:
Let it cool
Pour it into a sealable container such as a plastic bottle
Tightly seal the container to prevent spillage
Toss the container in your household garbage
Note: don’t use plastic bags, takeout containers, or aluminum cans to toss out used cooking oil or grease. While the oils may cool to a solid state, it’s not guaranteed to stay that way during transport, especially in warm climates. Liquified oil can easily spill out of a garbage bag and create a mess. Not only does this pose a risk to the environment, but it can be harmful if not incredibly annoying for waste management workers.
Take it to a recycling center near you
While oil recycling is not an option everywhere, many recycling centers and landfills have used oil recycling programs that accept cooking oil. The recycled cooking oil – from households as well as businesses such as restaurants – can be refined and converted into biofuels such as biodiesel or biogas.
The best way to find out if your municipality offers an oil recycling program is to go to your county’s recycling center website or call them directly.
If oil recycling is an option for you, simply collect your used cooking oil in a sealable container such as a plastic jug or empty jar and take it to the recycling center once you’ve collected a fair amount. Some programs even offer pickup.
Use an oil solidifier
National Geographic recently published an article about an innovative way to dispose of used cooking oil that is easy and safe: oil solidifiers.
Specifically: stearic acid. This long-chain fatty acid works by changing the density of the cooking oil into a solid state that can then be lifted out of the pot or pan and into the trash, without risk of leakage. An added benefit of this solid oil is that beneficial microbes can access it in the landfill and break it down – unlike oil trapped in a sealed container.
You can find stearic acid online or in some retail stores at a reasonable price.
Another commercially available oil solidifier is a product called FryAway. Although no specific ingredients are listed, it works the same as pure stearic acid and is conveniently packaged.
How do you dispose of used cooking oil? Tell us about your tips in the comments below!
