How Fat, Oil, and Grease from Winter Meals Can Lead to Blocked Drains

The winter season, with its festive holidays and colder temperatures, typically marks an increase in home cooking and large family meals. While this brings welcome warmth and tradition, it also introduces a significant and recurring problem for urban drainage systems: the excessive disposal of Fat, Oil, and Grease (FOG). As a dedicated London drainage company, Drainsmart understands that the period between late autumn and early spring sees a marked rise in call-outs for blockages directly attributable to FOG accumulation.

It is a common misconception that pouring hot cooking residues down the sink is a harmless method of disposal. The reality is that this practice is one of the most detrimental actions against a property’s plumbing and the wider sewer network. For property owners and facilities managers, understanding the transformation of liquid grease into a solid blockage is the key to preventing disruptive and expensive emergencies.

The Problem: From Liquid to Solid

When cooking oils and fats are hot, they maintain a fluid state, allowing them to flow relatively unimpeded through the kitchen sink and initial internal pipework. However, as they travel away from the heat of the sink and into the cooler environment of the drainage system—particularly the underground pipes where temperatures are consistently lower, especially during winter—they begin to cool rapidly.

This temperature drop causes the FOG to solidify. It adheres to the internal walls of the pipe, acting like a form of adhesive plaster. Over time, each successive discharge of grease builds upon the last, steadily reducing the diameter of the pipe. Furthermore, this sticky layer traps other non-biodegradable waste, such as food scraps, coffee grounds, and cleaning wipes, accelerating the formation of a dense, impenetrable mass. These accumulations, often referred to as ‘fatbergs’ when they occur in large public sewers, are just as problematic on a smaller scale within private drainage lines.

The Specific Winter Risk

The risk is amplified during the winter months for two primary reasons. Firstly, the aforementioned increase in large-scale domestic cooking generates significantly more grease—from turkey drippings and roast potato oil to copious amounts of butter and gravy residue. Secondly, the ground temperature surrounding underground pipes is naturally lower, hastening the solidification process. This means that a blockage that might take several months to form in the summer can develop far more quickly during a sustained period of cold weather.

The Consequences for London Properties

A FOG-induced blockage is rarely a slow-draining inconvenience; it is often a severe and immediate problem leading to foul water backing up into the property.

1. Foul Water Backflow: As the blockage becomes total, wastewater from sinks, dishwashers, and even toilets can no longer exit the property. The consequence is effluent backing up into the lowest-lying appliance or drain, causing immediate contamination and requiring professional deep cleaning and sanitation.

2. Damage to Internal Plumbing: The immense pressure exerted by wastewater against the blockage can stress pipe joints and seals, potentially leading to leaks within the fabric of the building that remain hidden until significant structural damage has occurred.

3. Health Hazards: Stagnant water and sewage within the system create an environment conducive to harmful bacteria and unpleasant odours, compromising the health and safety standards of the property.

Drainsmart’s Professional Intervention

At Drainsmart, we advocate for the responsible disposal of FOG—by pouring cooled grease into a container and disposing of it with household waste, not down the sink.

However, when a blockage inevitably occurs, professional intervention is essential. Our team is equipped with high-pressure water jetting equipment capable of breaking down and flushing out even the most stubborn fatbergs and accumulated debris. Learn more about our blocked drain clearance services in London.

Furthermore, for recurring or suspected chronic issues, we can provide CCTV drain surveys. These surveys utilise specialised camera technology to inspect the internal condition of the pipes, identify the precise location and extent of the FOG build-up, and detect any underlying structural defects, such as fractured pipes or displaced joints, that may be contributing to the issue.

Whether you require a comprehensive CCTV drain survey to diagnose a problem, or immediate blocked drain clearance in London, Drainsmart provides professional, timely, and effective solutions to restore the integrity and function of your drainage system throughout the challenging winter period.

If you suspect FOG accumulation or are experiencing slow drainage, please contact Drainsmart to schedule an inspection and prevent a serious winter blockage.