Fats, Oils, and Grease (FOG) are the collective terms for the lipids—animal fats and vegetable oils—that are a byproduct of cooking. While these substances are liquid when hot, they contain triglycerides that solidify and accumulate upon cooling. Proper disposal is necessary because FOG introduced into plumbing systems inevitably cools and congeals, leading to blockages. Managing FOG responsibly protects a home’s pipes and prevents environmental contamination in the greater sewer system.
Preparing Grease for Disposal
The initial step for handling used cooking oil or grease is to allow it to cool slightly, making it safer to manage while still in a liquid state. Immediately after cooking, FOG should be filtered through a fine-mesh strainer or cheesecloth to remove food particles, which can accelerate pipe blockages. This filtering also helps maintain the purity of the used oil if you plan to reuse or recycle it later.
For small amounts of grease, such as bacon fat or pan drippings, allow the material to solidify directly in the cooking vessel. Once the grease is firm, it can be scraped out with a spatula. For larger volumes of oil, like those from deep frying, the liquid must be poured into a collection container while still warm enough to flow easily.
Various durable, disposable containers can be used for collection, such as empty metal coffee cans, plastic yogurt containers, or the original plastic bottles the cooking oil came in. Using a container with a sealable lid, like an empty milk carton or a disposable coffee cup, prevents leaks and spills. The goal is to contain the FOG securely so it can be discarded with household waste.
Approved Disposal Techniques
The most common and effective method for disposing of small to moderate amounts of FOG is through the regular trash destined for a landfill. If the grease has solidified in its container, or if the liquid oil has been poured into a sealable vessel, it can be placed directly into the garbage bin. This technique ensures the material is contained and diverted away from the wastewater system entirely.
For solidified animal fats and greases, the material should be scraped out of the pan and into a disposable wrapper, such as newspaper or paper towels, before being tossed into the trash. Liquid oils poured into a container, such as a plastic jug or bottle, must have the lid tightly secured to prevent leakage. These measures prevent the oil from coating other waste materials or leaking out of the bag during transport.
For those with large volumes of used oil, such as from a turkey fryer, local recycling programs are often available. Many municipalities and rendering companies collect large batches of used cooking oil, processing it into biodiesel fuel or other industrial products. Composting is possible for very small amounts of plant-based oils, but animal fats should never be added as they attract rodents and pests. Adding vegetable oil in large quantities can also create a water-resistant barrier that slows the natural decomposition process.
Consequences of Improper Disposal
Pouring FOG down the sink, garbage disposal, or toilet initiates a damaging chain reaction that immediately affects household plumbing. As the warm liquid travels through the cold pipes, it cools and congeals, forming a sticky layer on the interior walls. This buildup rapidly narrows the pipe’s diameter and captures passing debris, leading to clogs that cause slow drains and sewage backups into the home.
Beyond the home, improperly disposed FOG travels into the municipal sewer system where it combines with other non-biodegradable waste to create massive obstructions known as “fatbergs.” These hardened masses can completely block sewer lines, leading to sanitary sewer overflows (SSOs) that spill untreated wastewater into streets and natural waterways. This contamination introduces pathogens and pollutants into the environment, harming aquatic life and water treatment facilities. The removal of fatbergs is a costly and complex operation for municipalities, a financial burden passed on to residents through higher utility rates.