FOG is a common by-product of food processing sites and food service establishments (FSEs) such as restaurants and takeaways, as well as domestic properties. Once disposed of via sinks and drains, it is usually considered a waste and can be highly problematic for sewage network operators.

In the UK it is illegal to discharge FOG to drains and sewers without proper kitchen equipment in place, such as grease traps that can screen it out before it meets the sewerage network.

If left to accumulate, FOG waste can block drains and sewers, risking sewer overflows, drainage backup and the flooding of properties, along with pollution of waterways and the environment.

According to a 2022 report from bioeconomy consultancy NNFCC, approximately 370,000 sewer blockages are reported annually in the UK, and up to 75% of these are understood to be directly caused by FOG. It is estimated that sewer blockages account for 80% of all sewer flooding in the UK, which results in over 5,000 properties being flooded.

Fatbergs are large masses of solid waste, comprising of congealed FOG combined with items that should not be flushed such as wet wipes and sanitary products.

In the UK it is a legal requirement to install grease traps or GRUs according to building regulations that comply with BS EN 1825-1:2004 standard, and are designed in accordance with BS En1825-2:2002 or other effective means of grease removal.

Recovered FOG should be stored in designated sealable containers and collected by a registered waste carrier.