Cooking oil is an ingredient that most of us use every day, but disposing of it in an environmentally friendly way is pretty tricky. This is because the consistency of oil can leave an oily residue on plants that makes it more difficult for them to absorb oxygen. Plus oil negatively impacts wildlife, too.

Even cooking oils that might be better for your body aren’t better for the environment. That said, disposing of oils in the safest way possible can help minimize their impact.

Firstly, what not to do

Before we get into what you should do with cooking oil, let’s make one thing clear: never throw cooking oil down the sink or flush it down the toilet. Not only will that clog your home plumbing system and negatively affect water flow, it will also send greasy oils into a septic tank or into your local water treatment plant. Most treatment facilities won’t be able to filter all the oil particles out, resulting in water tainted with grease being released back into the paths of plants and animals that should be getting fresh water.

Reuse the oil

Yes, that’s right, cooking oil can be used multiple times. If you want to store your cooking oil for later use, a simple glass jar should do the trick. For deep frying meat or fish, oil can be reused up to four times. For lighter foods like potatoes and other vegetables, you can get up to eight uses out of the same oil.

Cool it

No matter how you end up disposing of your oil, you must make sure it’s completely cooled down before getting rid of it. Freezing oil is a good method of saving it for later use or making the disposal process less messy. You could also place it in the fridge or leave it outside when the weather is cold to make sure it drops to an appropriate temperature for proper disposal.

Receptacle disposal

In some cases, the garbage bin is the only option available for getting rid of cooking oil. However, instead of just pouring cooking oil straight into the receptacle, it’s best to collect it in another non-recyclable container or bag. Just be careful not to poke a hole into the plastic (double bagging can’t hurt).

Local restaurants, fire stations, or recycling centers

Ask local restaurants what they’re doing to get rid of their oil waste. There might be a recycling service that converts used cooking oil for other uses, like car fuel.

You can also check in with a nearby fire department since many fire departments organize recycling programs for cooking oil and other hard-to-recycle household items. 

Finally, your local waste disposal company can offer another resource where you can call to ask about your options. 

Composting

For plant-based oil users, small amounts of oils can be beneficial to the compost ecosystem and may make worms and insects happy. However, this method should only be used if the oils were used to cook only vegetables and other non-animal foods. Don’t go overboard though, as too much oil will create that oxygen stifling layer we mentioned earlier.

Create solid waste

The main reason why oils are so difficult to dispose of is that they can be so messy. However, if you combine the oils with other waste materials (like sawdust, kitchen flour, kitty litter, or bedding from your pet hamster or rabbit) then the end result is a bit of solid waste that is easier for both you and local waste management professionals to handle.

Make soap out of it

This might seem counterintuitive, however, fat is a key ingredient in soap, so feel free to try high-fat cooking oils in a soap recipe. Of course, you’ll need to purify the dirty oil before adding it, but it’s well worth the effort as it will keep used cooking oil out of our landfills.

Make an insecticide

Remember when we mentioned that oil can limit oxygen and is bad for animals? Well, the same properties that make it a suffocating substance for wildlife make it an ideal ingredient for insecticides. If you mix oil in with soap and water, it can help prevent insects from ruining your crops.