There are still people who think that there's nothing wrong with pouring used cooking oil or its remnants down the sink and simply rinsing it away. Docent Dr. Ausra Zigmontiene from Vilnius Gediminas Technical University (VILNIUS TECH) Sustainability Center says that the consequences of such a habit are not just a constantly "clogged" sink and additional expenses for calling services to deal with such malfunctions but also significant damage to the environment.

What happens when we pour oil into the sink?

"Oil is a hydrophobic substance. This means that it cannot mix with water or dissolve in it. Oil poured into the sink or toilet, and entering the sewage pipes, can easily settle on the inner walls of the pipes as it flows along with the water. Over time, as it accumulates and solidifies, then clogs the entire pipe. Moreover, oil is sticky, so it can easily 'stick' to other substances in the pipeline - food particles, soap scum, or hair. This creates a thick and sticky mass that grows over time, clogging the sewage system and slowing down water flow," says Docent Dr. A. Zigmontiene.
According to her, the removal of such solidified oil and fat deposits is not only a complicated process but also requires spending a lot of money.

The impact on nature persist for years

Once the oil enters the sewer system, it doesn't disappear and continues its journey to wastewater treatment plants. The sustainability expert explains that this journey of oil can be hazardous to the environment.

"If the wastewater treatment plant is not equipped to effectively remove oil or fats, later such wastewater can contaminate surface water bodies, such as rivers or lakes. Oil, when it enters the water, forms a film on its surface, reducing the oxygen level in the water. This affects the balance of ecosystems and can harm aquatic life. Oil covering the gills of fish impairs their ability to breathe, and they can suffocate. What's worse, oil doesn't easily degrade in water. It can persist for years and continue to harm the environment and wildlife," says Docent Dr. Ausra Zigmontiene.

What to do with used oil?

To avoid accidents in sewage networks, clogged pipes, and environmental damage, the sustainability expert advises on environmentally friendly ways to dispose of oil:

"After cooking, let the oil cool, pour it into a plastic or glass container, and seal it tightly. In Lithuania, some regional waste management centres may provide special plastic containers for collecting used oil. The collected oil, unsuitable for further use, can be delivered to large waste collection sites throughout Lithuania. The collected oil can later be used as raw material for biofuel production. So, not only will you avoid unpleasant situations in your home, but you will also give the oil another chance to be useful," says Docent Dr. A. Zigmontiene.

Oil containers can be purchased and collected oil can be delivered to most large waste collection sites in Lithuania. Before taking the waste to the sites, it is advisable to contact the site staff, whose contacts can be found here. And if there's a small amount of oil left in the pan, it's advisable to wipe it with a paper towel and dispose of it in mixed waste containers. According to the sustainability expert, used paper towels will later be incinerated in waste incineration plants.
What to do if you accidentally poured oil into the sink?

"If you or your family members accidentally poured oil residues into the sink, don't rush to let the water run. Baking soda and vinegar will help you - pour baking soda into the sink drain, add vinegar, and wait for at least 10 minutes until the mixture 'bubbles up.' Then rinse everything with water. This will help protect the pipes from accidental oil spills," advises Docent Dr. A. Zigmontiene.

The sustainability expert reminds that the sink is not a garbage can. Not only oil or fats but also food residues, flour, coffee grounds, or hair should not be poured into it. According to her, all these types of waste not only cause unpleasant odours from the sink but also clog the pipes.
The VILNIUS TECH Sustainability Center was established in 2023 to strengthen competencies in the field of sustainability, foster a culture of sustainability, and responsibility for the environment and society. The activities of the Sustainability Center are supported by the ATHENA European Universities Alliance, a project funded by the Economic Recovery and Resilience Plan "New Generation Lithuania," and the Lithuanian state budget.