Cooking with oil of any variety — vegetable, canola, peanut, avocado, etc. — can delightfully transform the texture and flavor of food, but when it comes to cleaning up, getting rid of used oil can be less pleasant. And properly disposing of oil is important not just for your home's health, but also community and environmental health at large.
"The water that goes through our home drains or restaurant drains actually goes to the water treatment plant, is treated, and then we drink it. So we're ingesting that," says Jennifer Hill Booker, a professional chef, culinary educator, food advocate, and recent James Beard Foundation Impact Program Fellow under the Waste Not Initiative.
"If you're adding contaminants like oil to the water, it creates what's called FOG [fat, oil, and grease]," says Booker. "It takes a longer process [and] more chemicals to treat the water for us to then drink. It becomes unhealthy if we're adding a lot of oil [and] old grease to our water system."
Moreover, getting rid of oil the wrong way can attract pests and cause damage to your home. Following the correct methods ensures that you get the most out of your cooking oil and dispose of it in a way that's best for your home, your community, and the environment.
Containing and then throwing out cooking oil with the regular trash is a common and viable method for disposing of oil. After cooking, allow the oil to cool and then put it in a tightly sealed container. "That container could be the oil bottle or bucket that it came in initially, a Ziploc bag, or an old container out of the recycling bin," says Hill Booker.
"I do another step, where I make sure that it's ice cold," adds Hill Booker. She often freezes oil before putting it in the trash, especially "if it's during the warmer months. That way, I don't risk the container leaking or spilling out."
Freezing ahead of time also means that you can contain the oil with a biodegradable, instead of plastic, container: Oil in a solid state won't leak through biodegradable containers like liquid oil does.
If the oil has only been used once, you can clean, store, and reuse it in cooking. This stretches the life of oil before it's inevitably disposed of.
First, clean the cooled oil by straining it through a filter. Hill Booker prefers paper coffee filters: "[They're] very affordable, and they're easy on the environment."
After straining multiple times — Hill Booker usually does three — put the oil in a clean, airtight container and store it in the fridge. Never store used oil stored at room temperature, as it will spoil quickly. Properly stored, refrigerated cooking oil will last 30 days.
When it's time to use the stored oil, take out the amount needed and let it slowly come to a warmer temperature on the counter for 30 minutes or up to overnight. This "tempering," Hill Booker explains, is beneficial because "it takes less fuel to heat up the warm oil than it does a cold, right-out-of-the-fridge oil."
Most of the time, "you get two solid recycle uses," aka three total uses, of cooking oil. However, trust your senses for signs of spoilage more than counting uses: different oils break down on a chemical level at different rates, and break down results in less efficient and less healthy cooking. Three main signs that oil should not be reused are:
Keep in mind that oil takes on the taste and smell of the food it cooks. "If you're frying fish or onions or something like that, you wouldn't necessarily use it to cook something that is much more delicate, or has a much softer flavor or aroma," Hill Booker says. "If you're cooking vegetables for vegetarians or vegans, I wouldn't use oil that I've used to cook animal protein."
Also be aware of cross-contamination: For example, oil used to fry donuts shouldn't be used when cooking for someone with a gluten allergy.
Some recycling centers take cooking oil and treat it, for conversion into fuels like biodiesel or biogas. If you're unable to find reliable information about cooking oil recycling from your county's recycling center website, Hill Booker suggests calling whoever is responsible for your sanitation or water services. "They'll know where recycling centers are, and what kinds of items they take," she says.
She also recommends doing in-community research. "More and more people are finding ways to recycle oil," she says. "When I taught at the Le Cordon Bleu here in Atlanta, there was a gentleman who would come by and get our old fryer oil, and he had converted his engine to be able to work off … all types of vegetable oil."
Don't pour it down a home drain. "If you're pouring it down the drain, it's going to build up," says Hill Booker. "If you think about everything else you pour down the drains, you have soap scum, if you flush it down the toilet, you may have pieces oftoilet paperor waste. There might be hair in the drain that's come from your shower." Adding oil to the mix exacerbates that blockage, leading to clogs and pipe damage.
Following the oil with hot water doesn't make home drains more viable. The oil "doesn't make it all the way to the water treatment plant as a hot liquid," Hill Booker says, so at a certain point it will contribute to drain clogging, even if that clog occurs outside your home. And oil is detrimental to the water system anyway.
Don't pour it out in the yard. No matter what type of oil and what was cooked in it, used oil poured out in the yard will attract animals and pests, says Hill Booker. Because of this, it also "should not be part of your compost plan."
Don't pour it down a storm drain. Storm drains, like home drains, are not meant for oil disposal. Like pouring out in the yard, "you'll attract pests like rats and roaches," says Hill Booker, "and again, it's bad for the water system."
When disposing of cooking oil, don't pour it down drains or anywhere else where it can attract pests or get into water and sewage systems. This includes compost piles, which are already prone to attracting critters.
Instead, put used cooking oil in a tightly concealed container. Throw it out with the trash or take it, if it's accepted, to your local recycling center. Moreover, to get the most out of cooking oil, clean and store it for reuse a couple times before discarding.
"I would just say be prudent — that's the main thing," says Hill Booker. "Don't use more oil than you need to, because ultimately it all goes in the garbage, which we want to delay as much as possible."Mari HerremaAssociate Production Editor, ReferenceMari is an associate editor for the Editorial Production team on the Reference desk, where she works across three verticals — Tech, Health, and Home & Kitchen — to help maintain their ever-expanding archives. With experiences ranging from tech start-ups and film sets to coffeehouses and restaurant kitchens, Mari has an undying curiosity for understanding how things work and how to make that knowledge more accessible. When she's not writing, editing, or analyzing data, Mari's usually trying a new recipe, seeking out NYC bakeries, or reading a romance novel. She graduated from Brown University with a degree in English Literature.Read moreRead less