Maybe you’ve whipped up some fried chicken and waffles or golden, crisp-edged pakoras. After enjoying the meal, you’ll have to do something with the leftover oil. Starting with the obvious, you shouldn’t pour it down the drain or into the toilet.
Cooking fats, oils and grease are the main cause of clogged pipes and are among the top contributors to fatbergs, solid masses of waste that form in sewer systems. London’s “total monster” of a fatberg weighed 130 tonnes — ”the same as 11 double-decker buses” — and stretched more than 250 metres.
After a 64-metre fatberg ”the size of six double-decker buses” was found in Sidmouth, England, Andrew Roantree, director of wastewater at South West Water, issued a grave warning via The New York Times: “Put your pipes on a diet, and don’t feed the fatberg.”
How to throw away cooking fats, oils and grease
So, pouring fat down the drain — whether in the form of cooking oil, pan drippings, dairy products, soups, sauces, salad dressings, gravy or sandwich spreads — is a bad idea. Given the number of sewer back-ups and clogged pipes, it seems that the message hasn’t reached everyone.
The City of Calgary alone spends roughly $3 million every year to fix wastewater blockages and back-ups, primarily caused by pouring fats, oils and grease down the drain or into toilets. To dispose of small amounts of cooking oil, use a spatula or reuse a paper towel to scrape it into the compost or green bin. (The paper towel can go in, too.)
To dispose of larger amounts of cooking oil, allow it to cool. Then, scrape it gradually into your kitchen pail using the same method, only adding as much as the contents can absorb each day.
If you don’t have access to composting facilities, pour leftover fats into a used sealable container, such as a jug, tub or zipper bag, and throw it away.
It’s not readily available in Canadian communities, but cooking oil recycling is an ideal way to dispose of leftover fats. According to the Toronto Environmental Alliance, some multi-residential buildings have added this waste service to divert what it considers “a valuable resource that shouldn’t go to waste.” Used cooking oils can be recycled into biodiesel (the fate of London’s fatberg) or used as an animal feed ingredient.
Should you reuse cooking oil?
There are different opinions about the safety of reusing cooking oil. According to Serious Eats, “Oil for deep-frying should definitely, definitely be reused.” However, “The research into this subject presents a case for using fresh oil every time you cook,” writes Columbia Health’s Go Ask Alice.
When oil is heated, its chemical composition can change. The resulting “lipid degradation products” have been linked to a range of health issues, including cancer, liver disease and stroke.
“The issue becomes more prevalent when oil is reused,” according to Columbia Health. “It only takes one use to alter the composition of the oil, and reusing oil, especially at too high of a heat, can cause a build-up of harmful byproducts.”
If you must reuse cooking oil, use a thermometer to ensure it doesn’t overheat. Take it off the heat as soon as you’ve finished cooking, and once cool, strain the used oil through several layers of cheesecloth before storing the container in a cool, dark place.
Do oil solidifiers work?
Some products on the market solidify used cooking oil, making it easier to transfer from the pan to the compost or garbage. One Reddit user said of a Japanese oil solidifier, “Worked like a charm to dispose (of) the oil from shallow-frying tonkatsu.”
Consumer Reports reached a similar conclusion. Throwing away cooking oil in containers can be messy. Plastic tubs and bags are hardly infallible; they can break or leak. Solidified oil can be cleaner and more convenient — for you and your waste collector.
“Until curbside oil pickup comes to your neighbourhood, your best option for discarding used cooking oil is to solidify it.”
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