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What To Do with Old Cooking Oil

If you are a designated cook in your kitchen then you probably have a few questions about properly disposing and if you can even reuse cooking oil. I’ve often found myself pondering the same question, so what should we do with old cooking oil?

  • Throw it away down the drain? (Please Never do this)
  • Can You reuse it for cooking?
  • You can Make Soap?

Let over oil is just commonplace in the kitchen but many people fail to handle it appropriately. You might think pouring it down the sink or tossing it in the trash is an easy way out, but let me assure you, these methods can be harmful to the environment and can damage your plumbing.

So, what’s the solution?

tl;dr: There are a range of worthwhile options to handle used cooking oil, including reusing, recycling, composting, and converting into biofuel. An important step is always to let the oil cool down and store it properly. Before disposing of it, it might be useful to consider your local regulations about oil disposal.

Now, let’s dive in deeper and find out more about these options.

Dispose of it Correctly

If all else fails and you just need to dispose of your old cooking oil, it’s crucial to do it properly. While it might be tempting to pour it down the drain or toilet, this can lead to blockages and sewer issues, not to mention potential environmental damage and its the same with old engine oil.

Here’s a better way:

  1. Allow the oil to cool completely.
  2. Pour it into a sealable non-recyclable container, like an old plastic jug or tin can.
  3. Seal the container so it won’t leak.
  4. Dispose of the container with your regular household waste. If you’re unsure, check local regulations – some areas may have special requirements or facilities for disposing of cooking oil.

How to Reuse Your Old Cooking Oil

One of the most sustainable ways to deal with old cooking oil is to reuse it. It’s important to note, however, that not all cooking oil is suitable for reuse.

I recommend only reusing oil that has been used to fry vegetables or dough, as it is less likely to contain food particles that can spoil the oil.

Here are the steps to do this:

  1. Let the used oil cool down.
  2. Use a fine-mesh strainer or cheesecloth to filter out any food particles.
  3. Store the filtered oil in a clean, airtight container and keep it in a cool, dark place.

It’s advisable to reuse oil only a few times. If it starts to smell or appears dark and murky, it’s time to dispose of it.

Composting Old Oil

In small quantities, used vegetable-based cooking oil can be composted. It acts as a source of ‘brown’ material and helps to balance the ‘green’ materials like vegetable scraps.

It might be worthwhile to consider this option if you already have a compost pile at home. Remember, though, only use small amounts – too much oil can create a greasy layer that inhibits the composting process.

Biofuel Options

There are many facilities across the country that recycle used cooking oil. The oil is often converted into biofuel, which is a cleaner alternative to traditional fossil fuels. To recycle your cooking oil, I suggest following these steps:

  1. Store your used oil in a sturdy, leak-proof container.
  2. Locate your nearest recycling facility that accepts used cooking oil.
  3. Deliver your oil to the facility or arrange for pickup, depending on their policy.

Vegetable oil-powered engines is a great example that been around for decades

Additional Tips and Alternatives

A useful suggestion would be to reduce the amount of oil you use in the first place, as this will obviously result in less waste. Consider cooking methods like grilling, roasting, or steaming, which require less or no oil and in most cases it’s the healtier option.

Also, it’s worth noting that animal fats, unlike vegetable oils, solidify at room temperature. Instead of pouring these down the drain which can cause a clog, allow them to solidify, and then scrape them into a compost bin or the trash.

Innovative Ideas for Old Cooking Oil

You’d be surprised how many unique uses there are for old cooking oil! Here are a few of my personal favorites:

  • Make Soap: Saponification, the process of making soap, actually requires fats or oils. Used cooking oil can be a great, sustainable option. You’ll also need lye, water, and any essential oils or dyes you want for fragrance and color.
  • Create a Bird Feeder: Mix the used oil with bird seeds and fill a pinecone or other feeder. The oil is totally safe for the birds and can provide much-needed calories, especially in colder months.
  • Lubricate Tools and Machinery: Used cooking oil can be a handy lubricant for squeaky hinges, gardening tools, or small machinery.
  • Emergency Lamp Oil: You can make a simple oil lamp using a jar, a cotton wick, and used cooking oil. It’s a resourceful and economical solution when you’re in a pinch.
  • Fire Starter: Soak a piece of cloth in oil, and you have a reliable fire starter for camping trips or emergencies.

The Impact of Your Actions

In our global push towards sustainability, even small actions like how we handle our old cooking oil can have a profound impact. According to a report by the Environmental Protection Agency, recycling just one gallon of used cooking oil can produce enough biodiesel to run a diesel vehicle for 16 miles.

Consider the broader implications of your choices. Each decision to recycle, reuse, or properly dispose of used cooking oil can contribute to a healthier environment and more sustainable future.


As you can see, there are many viable options for what to do with old cooking oil. Reusing, recycling, composting, and even converting it into biofuel are all excellent ways to avoid wasting this valuable resource.

By properly managing our used cooking oil, we can not only keep our homes cleaner and safer but also contribute to the health of our planet.


Can old cooking oil be harmful?

Yes, if old or rancid oil is consumed, it can lead to health issues like food poisoning. Always smell and inspect the oil before reusing.

Can I put used oil in the compost bin?

Yes, but in limited quantities and only vegetable-based oil. It’s also better if the oil is free from any food particles.

How many times can I reuse cooking oil?

It depends on the type of oil and what it’s been used to cook, but typically, it can be reused 3-4 times. Always filter and store properly between uses.


  • Jen Wheeler

    Jen Wheeler, co-founder of Recycling-Revolution.com, holds degrees from UC Berkeley, Yale, and Stanford. A renowned environmentalist, she's championed sustainable practices at global events and leads EcoBright Solutions, focusing on recycling education and eco-friendly products.

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