How to Safely Dispose of Used Cooking Oil

Think back to the last time you cooked some food. Did you have any cooking oil or fat left once you were done? If you were roasting a chicken or frying some chips, the answer will almost certainly be yes.

So… what did you do with that fat afterwards?

If you’re like many other people, you may have poured it down the sink. Some people even pour it down the toilet, judging by some of the results our research efforts have turned up. However, neither option is correct or advisable.

Does grease and fat ruin plumbing?

Fats, oils and greases or FOG can certainly cause problems to plumbing installations, yes. Let’s return to that roast chicken for a second. When it’s freshly out of the oven, you remove it from its roasting dish, leaving all the juices behind. These will be liquid because they are hot, so it’s tempting to pour the lot down the sink, chased by plenty of hot water.

However, if you’ve ever left a roasting pan on the side to cool, you’ll know the fat will solidify. Chicken juices change into a jelly-like substance. It doesn’t take much effort to imagine how that will look in the pipework underneath your sink and underground drains. Other fats will solidify and cause blockages too, especially over time.

You may even get leaks if the fat is hot enough to burn the insides of the plastic sink pipes. If pouring hot oil down the sink is a regular occurrence, the build-up of unwanted oils, fats, greases, and other damage occurs over time.

Can you dissolve a fatberg?

A what? You did read that correctly. A fatberg is a mass of fats, oils, greases and other waste materials that have clogged a sewer, drain or pipe. You can get one in your home’s pipework if enough fat builds up over time, as described above.

But just imagine every home in your street – in your town or city – pouring fat down the drain too. This can lead to major fatbergs like the one that was discovered in a Whitechapel sewer in 2017. That one weighed an immense 140 tons.

Clearly, it sometimes takes more than a plunger and some hot water to dissolve some fatbergs. Avoiding them altogether is by far the better solution.

What happens when drains and sewers become blocked by fatbergs?

If you’ve ever experienced an overflowing drain on your property, you’ll know it can be a smelly and uncomfortable job to deal with. Some blockages can be cleared by the homeowner, while others require the expertise of a plumber, or drain cleaning specialist to clear.

But again, imagine the main sewers are blocked because many people living in the same street have all been pouring fat and oil down their sinks. This can lead to blockages of the sewers and serious issues at wastewater treatment plants. If home issues are pricey to fix, you can imagine these are worse still.

How do businesses dispose of waste oils and fats?

As you can imagine, the average hotel, restaurant or similar outlet can get through litres of cooking oil far faster than any house could manage. There are many commercial disposal services that handle commercial waste, including those specialising in cooking oil disposal. These must be authorised for collecting waste cooking oil.

How to dispose of used cooking oil at home

Firstly, consider whether you might be able to reuse the used cooking oil. You can usually use meat juices to make your own gravy, for example. Alternatively, you could keep the juices to make your own stock.

In any case, you should let it cool before using or disposing of it. If you want to use it later but cannot immediately do so, you can freeze it to defrost it later. This is ideal for juices to use in gravy or stocks.

Once it has cooled – and assuming you do not wish to use it for other purposes – you can get rid of it. You might assume you can put it into the caddy you use for food waste collection, but this isn’t usually the case. Oils are typically disposed of or recycled separately.

One option is to look at whether your local recycling centre allows for oil disposal from private householders. This can vary according to which council area you’re in and the services they provide. However, if you can get rid of it like this, find a big enough container to pour the oil into until you are ready to pay a visit. Just make sure it won’t be too heavy to pick up if you fill it before you go.

Another possibility is to combine the oil with some bird seed. This only works if the oil will solidify upon cooling though. If it will, you’ve got a quick way to recycle the oil that the birds will appreciate.

If none of that works for you, you can pour the waste oil or fat into a container and leave it to cool. Once it has fully cooled and solidified, you can pop it out and into your general waste bin. Some shops sell specially designed receptacles with cardboard liners, so you can pour cooled oil onto them. The oil soaks into the cardboard liner, which then goes into your bin when full. You can keep these oil traps on your worktop ready for use whenever you need them.

The bottom line? Avoid pouring hot fats and oils down the kitchen sink

If this still seems like the easiest way to get rid of any used cooking oils or fats you generate, you may come to regret it when the build-up of fat solidifies and blocks the pipework beneath your sink or the drains around your property. It may also contribute to a fatberg forming somewhere close by. That will also cause disruption if workers need to get into the sewers to break it down, causing hassle for days – if not weeks – on end.

Many people assume that boiling the kettle to melt the fat is a quick resolution. If you’ve ever had cause to try this, you’ll know it doesn’t tend to work. It may melt some around the edges, but that’s about it. Follow the recommendations above instead to dispose of it correctly.

Don’t become part of the next fatberg near you.

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