Can You Compost Cooking Oil?

If you’ve got a compost heap or bin and some used cooking oil, it might make sense to throw the latter into the former and let the organic material decompose in a natural way. Sadly, the compost cooking oil process isn’t quite that simple. Nor is the answer to: Can you compost cooking oil?

Here’s why… 

Can You Compost Cooking Oil?

Unfortunately, there isn’t a simple yes/no answer to this question. 

You can compost certain types of cooking oil, but you can’t compost others.

It is only recommended to add a small amount of cooking oil to your compost heap or bin at a time, too. And you’ll need to stir it more frequently, and keep the temperature high. 

Cooking oil and other oils will slow down the rate at which the waste turns to compost, and it can also disrupt the natural chemical processes that creates wonderful, nutrient-rich compost. Those aren’t the only things that’ll happen when you compost cooking oil, however. 

What Cooking Oils Can You Compost?

You should only add vegetable-based cooking oil to your compost heap or bin. And, as previously mentioned, you should only add very small amounts at a time. 

Gardening Know How recommends composting paper towels that have been soaked in oil rather than pouring a cup-full of used cooking oil all over the heap. 

The follow oils are safe and will compost in very small amounts: 

• Rapeseed oil
• Peanut oil
• Olive oil
• Sunflower oil
• Corn oil
• Sesame oil
• Coconut oil

What Cooking Oils Can’t Be Composted?

Some types of cooking oil will slow down the composting process considerably, and could even ruin the entire batch of compost you are trying to create.

Non-vegetable based cooking oils should not be added to compost heaps or bins. This includes synthetic cooking oils. 

Not only that, adding certain oils or high quantities of used cooking oil to compost heaps or bins will increase the stink-factor. It’ll smell awful, ruin your garden space and outdoor social events, and encourage predators and insects to come a little closer… which includes rats, mice, flies, and other pests. 

Can I Empty My Deep Fat Fryer into My Compost Bin?

No, you shouldn’t empty your deep fat fryer into your compost bin or heap. 

If you do this, you’ll be adding far too much cooking oil to the compost bin or heap than is recommended, and you are going to experience side effects as a result. This can include a vile smell, a higher temperature requirement, the need for more frequent stirring and aerating, attracting pest animals and insects, and a much slower rate of composting. 

If you add too much cooking oil to your compost bin or heap, you could even stop the composting process altogether, wasting all of the hard work you have already put into it. 

What Should You Do With Used Cooking Oil?

You do have a few options when it comes to getting rid of used cooking oil. Small amounts can be disposed of with household waste, and large amounts can be taken to food waste recycling centres, or recycling centres with a food waste feature. You can also create bird feeders with it, as well as a few other things. 

You can read about all of the disposal options in more detail right here: How to Properly Dispose of Cooking Oil UK.