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What to Do With Old Cooking Oil and Grease

Scientist and author, Beth is also a keen home cook. She enjoys trying new recipes.

Use a grease bag or plastic container to collect used kitchen oil and fat.

Use a grease bag or plastic container to collect used kitchen oil and fat.

3 Ways to Deal With Used Cooking Fats

  1. Reduce the amount of cooking grease and oil used.
  2. Reuse cleaned and filtered oils.
  3. Recycle for use as vehicle fuel, and animal feed.

1. Reduce the Amount of Cooking Grease and Oil Used

When cooking try and use as little oil or fat as possible. Use just enough oil to prevent the food from sticking to the pan, but not enough to drown it. You can buy spray cans of cooking oil that enable you to use just a tiny amount. It’s healthier for you to too; cook with less fat, and you may also lose weight.

If there’s a small amount of grease left in the pan or on the grill after cooking, then pour it into a grease disposal bag, or wipe it up with some paper kitchen towel. That way you can dispose of it in the general garbage rather than letting it join your detergent-filled dishwasher waste water down the drain.

2. Reuse Cleaned and Filtered Oil

To reuse cooking oil and grease you need to clean it, and remove any remnants of food from it. Do this by filtering the oil through a fine fabric like muslin or a paper towel. Place the oil in a muslin bag over a large container overnight, and allow the reclaimed oil to drip through the cloth by gravity. USDA (US Department of Agriculture) recommends that cleaned cooking oil is stored in the fridge and used within three months.

The bits sieved out of your used grease can be put in a grease disposal bag and then placed in your normal trash. Another way to sieve the dirty oil is by using some kitchen towel inside a plastic bag with some holes in it.

Two bluetits share a suet fat-ball.

Two bluetits share a suet fat-ball.

3. Recycle Into Vehicle Fuel and Animal Feed

Vehicle Fuel From Recycled Oil

Some restaurants and fast food businesses recycle their used cooking oil to create transport fuel. As an individual, you can also give your used fats to be recycled into fuel. The website Earth 911 has a useful search facility to help you find locations for used cooking oil drop-off points.

Animal and Bird Feed Using Recycled Cooking Grease

Some people pour their excess cooking fat into their pet dog’s feeding bowl. Others add the grease to food they leave out for feral cats. If you want to do this you should check first with your veterinarian that the grease is going to help and not harm that animal’s diet. A better use for used cooking oil and fats is to make fat balls for garden birds. This can really help wild birds survive a cold winter. Use a combination of nuts, seeds and waste cooking fat to make a fat ball feeder.

How to Make a Fat Ball Feeder for Garden Birds

  1. Store waste fats and oils in closed containers until fall.
  2. Use a disposable plastic cup or other mold to make the bird feeder.
  3. Before putting any grease in your mold, hold a piece of string or wire in the center of the mold. This will be used to attach your finished fat ball to a branch or bird feeder pole.
  4. Pour bird seed around the string or wire until the mold is nearly full. Leave a space of about an inch at the top.
  5. Pour the used melted grease or waste cooking oil over the seeds. The fat binds the seeds together.
  6. Place the full mold in a cold place for the fat to harden. As the fat cools, it expands and will fill the gap you left at the top of the mold.
  7. Cut away and remove the cup mold.
  8. Hang your seeded fat ball from a convenient branch and watch the birds enjoy their winter treat.
Cooking oil poured into a drain clogs pipes in your home and city sewers.

Cooking oil poured into a drain clogs pipes in your home and city sewers.

USDA Tips on Food Safety and Fat Reuse

The advice from the United States Department of Agriculture Food Safety and Inspection Service (USDA) on food safety and reusing cooking fats is as follows.

  1. If you intend to reuse your cooking oil. Strain it through a fine-weave cloth (muslin or cheesecloth), or sieve it to get rid of old food solids before reuse.
  2. Store used cooking oil for no longer than 3 months. Keep used fats refrigerated, and store them in a sealed container. Make sure you use them within 3 months, and then discard.
  3. If the oil is cloudy, has a foul odor or taste. DISCARD and do not use.
  4. The safe way to dispose of used grease. Pour it into a sealable metal container, and then throw the oil-filled container in the trash.
  5. Check for recycle oil drop-off points in your area. Your used fats can be used to make bio-diesel fuel or soap.

How Not to Dispose of COGs

Cooking oils and grease, known as COGs, are the dirty, used, cooking fats leftover after frying, broiling and grilling. Don’t be tempted to pour COGs down the kitchen sink. More than 80% of drain and sewer blockages are caused by an unpleasant mixture of kitchen fat congealed around used bathroom products like wet-wipes, and tampons.

Putting cooking oil, fats, and grease into a garden compost bin is another big no-no, as they attract vermin and flies. Septic tanks are also harmed if you put cooking oils into them; fat interferes with natural bacterial decomposition. The best solution to this oily problem is to “reduce, reuse, and recycle.” Only once these options are exhausted should you add any left-over fat residues to your household garbage for collection and disposal by the district waste authority.

Collect used oil from the skillet pan after frying, and clean or recycle.

Collect used oil from the skillet pan after frying, and clean or recycle.

What Are Fatbergs?

Fatbergs block sewers and cause big stink problems. They are massive balls of grease, fat, and excreta, combined with bathroom waste products like wet-wipes, cotton-wool buds, condoms, and diaper liners. Fatbergs snowball in size, becoming denser and more concrete-like as they grow. Eventually, they can move no further and get stuck. They are a nightmare to remove; they are rock-hard and smell of poo and rotten eggs. Think about the sewer-workers who have to clear these blockages, and dispose of your used cooking oil and grease in a better way.

Myth: Hot water and soap will break down oils and fats, keeping the pipe clear.

If you’ve blocked your drain, crossed fingers and a squirt of washing-up liquid won’t clear it. That’s because hot water and soap don’t dissolve oils and fats. The soap may actually harden in your pipes, sticking to other items and adding to the problem.

— Thames Water Authority

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

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