We’ve all been there, standing over the sink with a pot of oil, about it dump it down the drain, only to have a sink savvy friend or family member shout, “You can’t pour that down the sink!” You freeze and, unsure of what to do next, ask, “What should I do with it then?” The question hangs in the air for what feels like forever before the sink savior finally gives up, “I don’t know, just don’t pour it down the sink.”
As helpful as that experience was, whatever you ended up doing with the oil, it probably didn’t feel 100% right—I bet you had doubts the whole way through, didn’t you? Well, there are two general methods for “disposing" of that used cooking oil that will save your drain, and your brain—from ever having to think about this subject again.
The easiest and most economical way to “get rid” of your used cooking oil is simply to save and reuse it. You can reuse frying oil a few times on average (here’s a great guide if you have questions about that), just let it cool completely at room temperature, strain it through a coffee filter or cheese cloth into an airtight container, and keep it stored in a cool, dark place until you’re ready to fry again.
If the oil smells off or rancid, you should just throw it away—even it was only used once before.
Another thing to keep in mind when reusing cooking oil is that each time it’s used, the smoke point decreases, meaning the oil will start to burn and smoke earlier and at a lower temperature than the first time you used it.
How to Tell If You Can Reuse Your Cooking Oil
Depending on what oil you used and what you used it for, some cooking oils cannot or should not be saved for reuse. Any oil used to deep-fry is the perfect candidate for saving, but oils used to sear things like meat at high temperatures are not—they’re already “spent”, and it’s likely that you didn’t use enough to really make it worth the effort. If you shallow fry things like garlic, shallots, or onions and don’t need that cooking oil for the recipe, definitely strain and it save for later use—it would be great in a vinaigrette but could also be reused as the base oil for a simple curry or homemade mayonnaise.
Throw It Away
If your cooking oil doesn’t fall into the “reusable” category, that’s okay—you can throw it away. Instead of washing your oil down the sink, which after a time could cause the sink to become clogged thanks to a process called “saponification” that has a pretty horrifying consequence on a larger scale, simply let it cool completely at room temperature and pour it into a resealable, disposable container before popping it into the trash. Do not pour it directly into the trash bag (especially if it’s hot) and do not pour it into the toilet—something I’m kind of sad about even having to mention.
If you’d rather not throw it out with a container that could otherwise be recycled, don’t worry, you’ve got options. Depending on how much oil you have, you could let it cool, then use paper towels to soak it up before throwing the soaked towels away or cool it in the fridge until it hardens, then use a spoon to scoop the hardened oil directly into the trash.
If you have cats or access to plenty of sand or sawdust, you can also soak up the oil with cat litter, sand, or sawdust and throw it away like that.
Some areas have oil recycling options, so if you’re a big deep-frying fan and want to dig into that option—please do! Otherwise, reuse as much as you can, and then throw it away safely—for the sake of your sink, and sanity.