Disposing used cooking oil. Do's and Don'ts

Updated: Mar 16, 2021

Annually, in Malaysia, around 50,000 tons of used cooking oil are disposed off to the environment without proper treatment. This act contributes to water and soil contamination, which causes aquatic life disruption, sewer system blockages, cost increases for water treatment and waste management [1].

The discharge of used cooking oil into water bodies alters chemical processes in the water, one of them being the oxygen saturation. The oil forms a layer that covers the water surface and prevents oxygen dissolution. When the byproducts of oil degradation are mixed with water they increase the chemical oxygen demand of the water and contaminate the water to be toxic. Consequently, the aquatic lives absorbed poisonous compounds from the polluted water and later returned to humans through the food chain [2].


Whether deep-frying or browning meat, we often end up with leftover cooking oil. The extent to which Malaysians employ the frying method in food preparations results in generating huge quantities of waste cooking oil.

Here are the Do's and Don'ts of Disposing Used Cooking Oil:

DON'T Pour oil down the drain or in the toilet. It can and it will clog your pipes.

DO Reuse Cooking Oil. If you fry foods on a regular basis, you can save the cooking oil to use again. Please note that you must first strain the oil (you can use a coffee filter or a cloth), then pour it into a glass airtight container and store it until ready to use. It is important to note that you should reuse oil only once or twice (each time you reuse the oil, the oil deteriorates, and the temperature at which it will burn decreases).

DON'T Pour hot oil into the trash can, as it can attract insects and rodents.

DO Pour into a disposable container. If you want to get rid of the oil, first let the oil cool completely, then pour it into a non-recyclable container with a lid and throw it in the garbage.

If you prefer throwing it without a container, then you need to freeze or refrigerate the oil first to harden it. Pour the oil into an old can and put it in the freezer or fridge. Once the oil is solid enough to come out of the can in one piece, it is ready to be thrown into the trash.

DON'T Dispose of cooking oil into compost bins or piles. Fats, in general, are bad for compost as not will attract vermin but they also tend to coat your organic materials with a water-resistant barrier, which will slow down the decomposition process.

DO Combine with other solid waste material. Before disposing of the oil, you can mix it with an absorbent material like cat litter, sand, flour and sawdust, which easily soaks up the liquid.

e.g. You can save old oil in a used container until it is time to empty the litter box; dump the oil into the litter and create a mix until the consistency is thick enough to throw away.

DON'T Add oil to a septic system. It can clog pipes and, even worse, your distribution lines and drainage field. Water contaminated with oil is difficult—sometimes impossible—to treat.



[1]. Chen, Y., Xiao, B., Chang, J., Fu, Y., Lv, P., & Wang, X. (2009). Synthesis of biodiesel from waste cooking oil using immobilized lipase in fixed bed reactor. Energy conversion and management, 50(3), 668-673.

[2]. Kulkarni, M. G., & Dalai, A. K. (2006). Waste cooking oil an economical source for biodiesel: a review. Industrial & engineering chemistry research, 45(9), 2901-2913.

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