You might have heard that oil and water do not mix–perhaps figuratively or literally. Scientifically, oil and water really do not mix. Neither do grease and your kitchen sink. The composition of any oil is unsuitable for your sink. Typical cooking oils have distinct properties and characteristics that can damage your kitchen’s plumbing.

When making a decision on how to discard oil correctly, your kitchen sink is not the answer.

Image depicting the improper disposal of cooking oil, with oil being poured directly into a kitchen sink, a practice that can lead to significant plumbing issues

First and foremost (and obvious), oil is insoluble in water, meaning that the oil will not dissipate in water alone. People often make the mistake of running hot water as used oil is poured down the drain. While this may help the oil to flow smoothly away, the fact is that oil will not dissipate with the hot water, and the addition of dish soap will not aid this solution. Dish soap emulsifies the composition of oil and grease, breaking the oil into fine droplets that can easily be washed away but not properly removed.

The viscosity of oil is higher than that of water, making it difficult to flow. Once the water supply is shut off, oil will solidify into its original state when cooled. This causes clogging in your drain. Overtime, grime and bacteria accumulate along the walls of your kitchen’s piping system. Oil can build upon these previous blockages which not only becomes a difficult clog to remove, but can cause more serious damage in the long run as well.

Pipe Damage

As said previously, different oils have different properties and characteristics. Oils can degrade or corrode pipes, causing cracks, leaking, or collapse. This can lead to costly repairs or replacements. These fixtures can also cause future disturbances in your current plumbing system.


When oil enters the sewage system, it can contribute to the formation of fatbergs. Fatbergs are large masses of congealed fat, oil, grease, and other debris that accumulate in sewer pipes. These blockages can cause sewage backups, leading to unpleasant odors, health hazards, and environmental contamination… or the plot start for the next Ghostbusters movie.

Environmental Impact

When oil enters the water supply, whether through plumbing leaks or improper disposal, it can have detrimental effects on the environment. Oil pollution can harm aquatic life, contaminate water sources, and damage ecosystems. Additionally, oil spills or leaks (of any kind) can have severe consequences for the environment, including soil and water contamination.

Plumbing System Maintenance

Dealing with oil-related plumbing issues requires time, effort, and money. Regular maintenance and cleaning of pipes may be necessary to prevent or address clogs caused by oil. This can involve professional assistance, specialized equipment, and disruptive interventions in your plumbing system.

How to Properly Dispose Oil

Before moving forward with the disposal of oil at home, allow the oil to cool before handling. Hot oil can not only burn or seriously injure, but it will also destroy plastic. Once the oil is cooled, you may then use a sturdy plastic or glass container with a well-sealable lid. Save your empty milk cartons or coffee cans to use as a cost effective container for disposing of oil. Consider filtering the oil if it is in a condition to be reused. Clearly label the container “Used Oil” for future use.

Do research to ensure that proper regulations are followed according to your location. Some locations have specific guidelines on handling and recycling used oil. Check with your local waste management or recycling center to find out if they accept used oil. Many recycling centers have designated collection points for used oil where you can drop it off.

For those who are unsure where to recycle their used oil, the Earth911 Recycling Guide provides a helpful tool for locating recycling centers in your area that accept used oil. You can access this tool via the following link: How to Recycle Cooking Oil.

Remember, improper disposal of oil can have significant negative consequences on the environment and your plumbing, so it’s important to follow the appropriate disposal methods to protect both your plumbing system and the ecosystem.