Fat is an essential part of our diets (in moderation) and also an integral part of the food preparation process, whether that’s tossing a healthy salad in olive oil or deep frying some slightly-less-healthy French fries. Some fats are either absorbed during cooking or form part of the meal itself, adding flavor, but others such as cooking oil are left over after cooking. And it can be confusing as to what you’re supposed to do with these types of food waste. 

In this guide, we’ll tell you everything you need to know about how to recycle, reuse or safely dispose of cooking oil. If you use oil regularly during cooking, this is an essential part of the process. And disposing of oil incorrectly can lead to serious issues both for your property and the wider municipal infrastructure. That’s because hot oil or grease will solidify when cooled, clog up wastewater pipes and sewers, and lead to very unpleasant blockages. In fact, incorrect disposal of fats and oils on a large scale has led to the phenomenon of ‘fatbergs’. These are huge masses of fat, grease, and oil that build up in sewers, causing huge amounts of damage and requiring costly removal.

So, just what should you do with cooking oil and other fats once used? Is it possible to put used cooking oil to good use elsewhere? And how can we all use less cooking oil in our food? Keep reading to find answers to these FAQs and more.


Why should you recycle cooking oil?

Cooking oil possesses something called British Thermal Unit, or BTU, which is the measure of the heat content of any energy source. This means that once filtered and cleaned it can be recycled to make other products. This can include things like cosmetics, stockfeed, biodiesel, and more. So, even after it’s been through the fryer a few times, cooking oil still has a wide range of potential uses and should never simply be discarded. This applies to almost all kinds of cooking oils.


Simple and easy steps for recycling cooking oil 

It’s worth pointing out that small amounts of cooking oil can be cleaned away from the pan using paper towels before washing up and then discarded. But any amount of cooking oil that pools needs to be dealt with correctly. And the best way to do that is recycling.

First, you need to let the cooking oil cool down completely before you try to do anything with it. Oil can reach extremely high temperatures during cooking and can be very dangerous, so never try to deal with it until it reaches room temperature.

You should ideally strain your oil to remove any larger food scraps using a sieve. This will also help to prevent mold and bad smells developing in the stored oil. You need to have a suitable container to keep all your used oil too. Ideally, this will not be plastic as these can crack, leak, and even melt if the oil is still hot. A large glass jar is usually a good choice.

When your container is full, you should take it to a suitable recycling center drop off that accepts recycled oil. Ideally, you should only store the oil for three to four weeks before taking it to the recycling center. Depending on your location and the amount of used cooking oil you have to recycle, there may be oil pickup service you can use. This is particularly useful for commercial kitchens that produce a lot of waste cooking oil.


Different ways to reuse cooking oil

As alluded to above, there are many ways that you can reuse oil and other cooking fats.



One of the most common is in the production of biofuels, as an alternative to petroleum, which can be used to power vehicles and even heat homes. Biofuels can reduce carbon emissions by up to 85% per gallon.


Animal feed

Cooking oil still contains a lot of nutrition and can be used to make various types of animal and pet food. The nutrients in these oils may even be what makes your dog or cat’s coat shiny.



Some types of cooking oils, such as vegetable oil, can be composted in small quantities. However, this can only be done gradually, as adding too much to your compost pile may cause a foul odor and attract rodents.



Most soaps need some kind of oil to bind the ingredients together and cause foaming.



Many cosmetic products such as shampoo and conditioner use oil to moisturize, soften hair and leave a shine, in much the same way they do for our pets.


Cleaning products

Many cleaning products have a certain quantity of oil, especially furniture cleaners and polishes.


The list of uses for recycled oils goes on and on, which is why recycling is such a good idea.


How to dispose of cooking oil

As mentioned above, oil should be allowed to cool thoroughly before being strained or sieved into a suitable container. This should be collected for a period of no more than four weeks before being taken to an appropriate recycling center to be dealt with at a larger scale. 

Very small amounts of cooking oil can either be wiped away using paper towels or added to your compost (vegetable oils only).


How NOT to dispose of cooking oil and grease

You should never pour any amount of cooking oil either down the sink or into the garbage disposal. As oil and grease cool they solidify and may cling to the inside of your pipes. It will not wash away easily, even with hot water, and this may cause blockages, bad odors, or other plumbing issues. Of course, there may be some residual oil on dishes or other cookware which will be cleaned away when washing up. Having a grease trap in your plumbing system will help to collect and remove this problem as it builds up over time.  


Why is discarding cooking oil a problem?

Repeated pouring of oil down the drains can cause blockages over time which can damage and even rupture pipes. This can lead to costly and inconvenient plumbing repairs, as well as water damage to your home. At a wider level, the same can happen to municipal sewers and drains which can cause disruption, unpleasant backing up, fatbergs, and ultimately higher local maintenance rates and taxes.


Tips for using less cooking oil

Of course, the best way to reduce the amount of cooking oil you need to deal with is to use less. There are some easy tips and tricks to cut down, including using non-stick pans and utensils, cooking your food in a different way (such as grilling or steaming), or using water to sauté your food instead of oil.



Cooking oil is very useful in the kitchen and can help us create tasty and delicious food. We’re not advocating cutting it out of our diets completely but reducing the amount of oil we use is a good way to stay healthy. Crucially, when we do use oil, it’s very important to deal with the leftovers in the correct way. That means you should never pour cooking oil down the drain or garbage disposal, instead storing it correctly and taking it to the appropriate recycling services so that it can be reused in the right way. Waste cooking oil should be treated in the same way as any other household hazardous waste – with the care and respect it deserves.


If you would like more information about how to deal with food waste, as well as other domestic or commercial sustainability matters, then check out the RTS blog and our core services here.

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