Can I reuse frying oil, and how do I get rid of it?

Frying oil is expensive to buy and expensive to waste, and it degrades gradually rather than suddenly. Knowing what to look for lets you use it several times without the food tasting of it.

Safety

Step by step

1. Let it cool to warm before straining.Warm enough to pour easily, cool enough to be safe — around an hour after frying. Never pour hot oil into plastic.
2. Strain it through fine mesh or muslin.Food particles are what make oil break down and taste burnt. A fine sieve lined with muslin or kitchen paper takes out almost everything.
3. Store it in a sealed container, cool and dark.A clean glass jar or the original bottle, in a cupboard, not next to the hob. Light and heat accelerate rancidity.
4. Label it with what you fried.Oil takes on flavour. Oil used for fish should be kept for fish. Oil used for doughnuts should not go near battered cod.
5. Reuse it three or four times for most frying.More for oil used at lower temperatures with clean food, fewer for heavily battered or breadcrumbed items, which shed particles.
6. Know the signs it is finished.Dark and syrupy, foaming at the surface when hot, smoking well below its normal smoke point, or a rancid, fishy or acrid smell. Any one of those means bin it.
7. Never pour it down the drain.It congeals in the pipes and in the sewer. Blocked household drains are the immediate consequence and fatbergs are the collective one.
8. Bin small amounts sealed.Cool it, pour it into an empty plastic bottle or a sealed tub, and put it in general waste. A small quantity can also be soaked into kitchen paper and binned.
9. Take larger amounts to a recycling centre.Most UK household waste recycling centres accept cooking oil, and some councils collect it. It is turned into biodiesel.
10. Do not compost it or pour it on the garden.It attracts vermin, coats soil so water cannot penetrate, and does not break down usefully.

Tips

• Strain it while warm. Cold oil is thick and takes forever through a sieve.
• Keep separate jars for fish oil and everything else.
• An old plastic bottle with a screw cap is the easiest way to bin waste oil.

Common mistakes

• Pouring oil down the sink with hot water — The hot water only carries it a few metres before it cools, congeals and sticks to the pipe. Repeated over months it narrows the pipe until it blocks entirely, and it is a major contributor to sewer blockages.
• Reusing oil that has gone dark and foams when heated — Those are signs the oil has broken down into compounds that taste acrid and smoke at much lower temperatures, so food fried in it burns on the outside and tastes stale.

If it doesn't work

Questions people ask